713 lines
20 KiB
C
713 lines
20 KiB
C
/* File I/O for GNU DIFF.
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Copyright (C) 1988, 1989, 1992, 1993, 1994 Free Software Foundation, Inc.
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This file is part of GNU DIFF.
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GNU DIFF is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU DIFF is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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*/
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#include "diff.h"
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/* Rotate a value n bits to the left. */
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#define UINT_BIT (sizeof (unsigned) * CHAR_BIT)
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#define ROL(v, n) ((v) << (n) | (v) >> (UINT_BIT - (n)))
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/* Given a hash value and a new character, return a new hash value. */
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#define HASH(h, c) ((c) + ROL (h, 7))
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/* Guess remaining number of lines from number N of lines so far,
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size S so far, and total size T. */
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#define GUESS_LINES(n,s,t) (((t) - (s)) / ((n) < 10 ? 32 : (s) / ((n)-1)) + 5)
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/* Type used for fast prefix comparison in find_identical_ends. */
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#ifndef word
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#define word int
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#endif
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/* Lines are put into equivalence classes (of lines that match in line_cmp).
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Each equivalence class is represented by one of these structures,
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but only while the classes are being computed.
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Afterward, each class is represented by a number. */
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struct equivclass
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{
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int next; /* Next item in this bucket. */
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unsigned hash; /* Hash of lines in this class. */
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char const *line; /* A line that fits this class. */
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size_t length; /* That line's length, not counting its newline. */
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};
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/* Hash-table: array of buckets, each being a chain of equivalence classes.
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buckets[-1] is reserved for incomplete lines. */
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static int *buckets;
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/* Number of buckets in the hash table array, not counting buckets[-1]. */
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static int nbuckets;
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/* Array in which the equivalence classes are allocated.
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The bucket-chains go through the elements in this array.
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The number of an equivalence class is its index in this array. */
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static struct equivclass *equivs;
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/* Index of first free element in the array `equivs'. */
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static int equivs_index;
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/* Number of elements allocated in the array `equivs'. */
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static int equivs_alloc;
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static void find_and_hash_each_line PARAMS((struct file_data *));
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static void find_identical_ends PARAMS((struct file_data[]));
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static void prepare_text_end PARAMS((struct file_data *));
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/* Check for binary files and compare them for exact identity. */
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/* Return 1 if BUF contains a non text character.
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SIZE is the number of characters in BUF. */
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#define binary_file_p(buf, size) (memchr (buf, '\0', size) != 0)
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/* Get ready to read the current file.
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Return nonzero if SKIP_TEST is zero,
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and if it appears to be a binary file. */
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int
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sip (current, skip_test)
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struct file_data *current;
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int skip_test;
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{
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/* If we have a nonexistent file at this stage, treat it as empty. */
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if (current->desc < 0)
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{
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/* Leave room for a sentinel. */
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current->bufsize = sizeof (word);
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current->buffer = xmalloc (current->bufsize);
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}
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else
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{
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current->bufsize = STAT_BLOCKSIZE (current->stat);
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current->buffer = xmalloc (current->bufsize);
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if (! skip_test)
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{
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/* Check first part of file to see if it's a binary file. */
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#if HAVE_SETMODE
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int oldmode = setmode (current->desc, O_BINARY);
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#endif
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size_t n = read (current->desc, current->buffer, current->bufsize);
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if (n == -1)
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pfatal_with_name (current->name);
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current->buffered_chars = n;
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#if HAVE_SETMODE
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if (oldmode != O_BINARY)
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{
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if (lseek (current->desc, - (off_t) n, SEEK_CUR) == -1)
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pfatal_with_name (current->name);
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setmode (current->desc, oldmode);
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current->buffered_chars = 0;
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}
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#endif
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return binary_file_p (current->buffer, n);
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}
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}
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current->buffered_chars = 0;
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return 0;
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}
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/* Slurp the rest of the current file completely into memory. */
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void
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slurp (current)
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struct file_data *current;
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{
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size_t cc;
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if (current->desc < 0)
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/* The file is nonexistent. */
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;
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else if (S_ISREG (current->stat.st_mode))
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{
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/* It's a regular file; slurp in the rest all at once. */
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/* Get the size out of the stat block.
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Allocate enough room for appended newline and sentinel. */
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cc = current->stat.st_size + 1 + sizeof (word);
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if (current->bufsize < cc)
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{
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current->bufsize = cc;
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current->buffer = xrealloc (current->buffer, cc);
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}
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if (current->buffered_chars < current->stat.st_size)
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{
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cc = read (current->desc,
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current->buffer + current->buffered_chars,
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current->stat.st_size - current->buffered_chars);
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if (cc == -1)
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pfatal_with_name (current->name);
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current->buffered_chars += cc;
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}
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}
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/* It's not a regular file; read it, growing the buffer as needed. */
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else if (always_text_flag || current->buffered_chars != 0)
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{
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for (;;)
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{
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if (current->buffered_chars == current->bufsize)
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{
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current->bufsize = current->bufsize * 2;
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current->buffer = xrealloc (current->buffer, current->bufsize);
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}
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cc = read (current->desc,
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current->buffer + current->buffered_chars,
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current->bufsize - current->buffered_chars);
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if (cc == 0)
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break;
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if (cc == -1)
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pfatal_with_name (current->name);
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current->buffered_chars += cc;
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}
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/* Allocate just enough room for appended newline and sentinel. */
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current->bufsize = current->buffered_chars + 1 + sizeof (word);
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current->buffer = xrealloc (current->buffer, current->bufsize);
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}
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}
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/* Split the file into lines, simultaneously computing the equivalence class for
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each line. */
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static void
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find_and_hash_each_line (current)
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struct file_data *current;
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{
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unsigned h;
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unsigned char const *p = (unsigned char const *) current->prefix_end;
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unsigned char c;
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int i, *bucket;
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size_t length;
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/* Cache often-used quantities in local variables to help the compiler. */
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char const **linbuf = current->linbuf;
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int alloc_lines = current->alloc_lines;
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int line = 0;
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int linbuf_base = current->linbuf_base;
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int *cureqs = (int *) xmalloc (alloc_lines * sizeof (int));
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struct equivclass *eqs = equivs;
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int eqs_index = equivs_index;
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int eqs_alloc = equivs_alloc;
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char const *suffix_begin = current->suffix_begin;
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char const *bufend = current->buffer + current->buffered_chars;
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int use_line_cmp = ignore_some_line_changes;
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while ((char const *) p < suffix_begin)
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{
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char const *ip = (char const *) p;
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/* Compute the equivalence class for this line. */
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h = 0;
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/* Hash this line until we find a newline. */
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if (ignore_case_flag)
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{
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if (ignore_all_space_flag)
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while ((c = *p++) != '\n')
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{
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if (! ISSPACE (c))
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h = HASH (h, ISUPPER (c) ? tolower (c) : c);
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}
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else if (ignore_space_change_flag)
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while ((c = *p++) != '\n')
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{
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if (ISSPACE (c))
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{
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for (;;)
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{
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c = *p++;
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if (!ISSPACE (c))
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break;
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if (c == '\n')
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goto hashing_done;
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}
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h = HASH (h, ' ');
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}
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/* C is now the first non-space. */
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h = HASH (h, ISUPPER (c) ? tolower (c) : c);
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}
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else
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while ((c = *p++) != '\n')
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h = HASH (h, ISUPPER (c) ? tolower (c) : c);
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}
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else
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{
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if (ignore_all_space_flag)
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while ((c = *p++) != '\n')
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{
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if (! ISSPACE (c))
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h = HASH (h, c);
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}
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else if (ignore_space_change_flag)
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while ((c = *p++) != '\n')
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{
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if (ISSPACE (c))
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{
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for (;;)
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{
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c = *p++;
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if (!ISSPACE (c))
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break;
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if (c == '\n')
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goto hashing_done;
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}
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h = HASH (h, ' ');
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}
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/* C is now the first non-space. */
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h = HASH (h, c);
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}
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else
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while ((c = *p++) != '\n')
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h = HASH (h, c);
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}
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hashing_done:;
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bucket = &buckets[h % nbuckets];
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length = (char const *) p - ip - 1;
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if ((char const *) p == bufend
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&& current->missing_newline
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&& ROBUST_OUTPUT_STYLE (output_style))
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{
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/* This line is incomplete. If this is significant,
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put the line into bucket[-1]. */
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if (! (ignore_space_change_flag | ignore_all_space_flag))
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bucket = &buckets[-1];
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/* Omit the inserted newline when computing linbuf later. */
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p--;
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bufend = suffix_begin = (char const *) p;
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}
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for (i = *bucket; ; i = eqs[i].next)
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if (!i)
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{
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/* Create a new equivalence class in this bucket. */
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i = eqs_index++;
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if (i == eqs_alloc)
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eqs = (struct equivclass *)
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xrealloc (eqs, (eqs_alloc*=2) * sizeof(*eqs));
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eqs[i].next = *bucket;
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eqs[i].hash = h;
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eqs[i].line = ip;
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eqs[i].length = length;
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*bucket = i;
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break;
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}
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else if (eqs[i].hash == h)
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{
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char const *eqline = eqs[i].line;
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/* Reuse existing equivalence class if the lines are identical.
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This detects the common case of exact identity
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faster than complete comparison would. */
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if (eqs[i].length == length && memcmp (eqline, ip, length) == 0)
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break;
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/* Reuse existing class if line_cmp reports the lines equal. */
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if (use_line_cmp && line_cmp (eqline, ip) == 0)
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break;
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}
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/* Maybe increase the size of the line table. */
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if (line == alloc_lines)
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{
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/* Double (alloc_lines - linbuf_base) by adding to alloc_lines. */
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alloc_lines = 2 * alloc_lines - linbuf_base;
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cureqs = (int *) xrealloc (cureqs, alloc_lines * sizeof (*cureqs));
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linbuf = (char const **) xrealloc (linbuf + linbuf_base,
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(alloc_lines - linbuf_base)
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* sizeof (*linbuf))
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- linbuf_base;
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}
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linbuf[line] = ip;
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cureqs[line] = i;
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++line;
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}
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current->buffered_lines = line;
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for (i = 0; ; i++)
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{
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/* Record the line start for lines in the suffix that we care about.
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Record one more line start than lines,
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so that we can compute the length of any buffered line. */
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if (line == alloc_lines)
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{
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/* Double (alloc_lines - linbuf_base) by adding to alloc_lines. */
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alloc_lines = 2 * alloc_lines - linbuf_base;
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linbuf = (char const **) xrealloc (linbuf + linbuf_base,
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(alloc_lines - linbuf_base)
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* sizeof (*linbuf))
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- linbuf_base;
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}
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linbuf[line] = (char const *) p;
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if ((char const *) p == bufend)
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break;
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if (context <= i && no_diff_means_no_output)
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break;
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line++;
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while (*p++ != '\n')
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;
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}
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/* Done with cache in local variables. */
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current->linbuf = linbuf;
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current->valid_lines = line;
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current->alloc_lines = alloc_lines;
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current->equivs = cureqs;
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equivs = eqs;
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equivs_alloc = eqs_alloc;
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equivs_index = eqs_index;
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}
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/* Prepare the end of the text. Make sure it's initialized.
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Make sure text ends in a newline,
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but remember that we had to add one. */
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static void
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prepare_text_end (current)
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struct file_data *current;
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{
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size_t buffered_chars = current->buffered_chars;
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char *p = current->buffer;
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if (buffered_chars == 0 || p[buffered_chars - 1] == '\n')
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current->missing_newline = 0;
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else
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{
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p[buffered_chars++] = '\n';
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current->buffered_chars = buffered_chars;
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current->missing_newline = 1;
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}
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/* Don't use uninitialized storage when planting or using sentinels. */
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if (p)
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bzero (p + buffered_chars, sizeof (word));
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}
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/* Given a vector of two file_data objects, find the identical
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prefixes and suffixes of each object. */
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static void
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find_identical_ends (filevec)
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struct file_data filevec[];
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{
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word *w0, *w1;
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char *p0, *p1, *buffer0, *buffer1;
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char const *end0, *beg0;
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char const **linbuf0, **linbuf1;
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int i, lines;
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size_t n0, n1, tem;
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int alloc_lines0, alloc_lines1;
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int buffered_prefix, prefix_count, prefix_mask;
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slurp (&filevec[0]);
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if (filevec[0].desc != filevec[1].desc)
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slurp (&filevec[1]);
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else
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{
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filevec[1].buffer = filevec[0].buffer;
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filevec[1].bufsize = filevec[0].bufsize;
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filevec[1].buffered_chars = filevec[0].buffered_chars;
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}
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for (i = 0; i < 2; i++)
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prepare_text_end (&filevec[i]);
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/* Find identical prefix. */
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p0 = buffer0 = filevec[0].buffer;
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p1 = buffer1 = filevec[1].buffer;
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n0 = filevec[0].buffered_chars;
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n1 = filevec[1].buffered_chars;
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if (p0 == p1)
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/* The buffers are the same; sentinels won't work. */
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p0 = p1 += n1;
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else
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{
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/* Insert end sentinels, in this case characters that are guaranteed
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to make the equality test false, and thus terminate the loop. */
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if (n0 < n1)
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p0[n0] = ~p1[n0];
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else
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p1[n1] = ~p0[n1];
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/* Loop until first mismatch, or to the sentinel characters. */
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/* Compare a word at a time for speed. */
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w0 = (word *) p0;
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w1 = (word *) p1;
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while (*w0++ == *w1++)
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;
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--w0, --w1;
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/* Do the last few bytes of comparison a byte at a time. */
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p0 = (char *) w0;
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p1 = (char *) w1;
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while (*p0++ == *p1++)
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;
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--p0, --p1;
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/* Don't mistakenly count missing newline as part of prefix. */
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if (ROBUST_OUTPUT_STYLE (output_style)
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&& (buffer0 + n0 - filevec[0].missing_newline < p0)
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!=
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(buffer1 + n1 - filevec[1].missing_newline < p1))
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--p0, --p1;
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}
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/* Now P0 and P1 point at the first nonmatching characters. */
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/* Skip back to last line-beginning in the prefix,
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and then discard up to HORIZON_LINES lines from the prefix. */
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i = horizon_lines;
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while (p0 != buffer0 && (p0[-1] != '\n' || i--))
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--p0, --p1;
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/* Record the prefix. */
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filevec[0].prefix_end = p0;
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filevec[1].prefix_end = p1;
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/* Find identical suffix. */
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/* P0 and P1 point beyond the last chars not yet compared. */
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p0 = buffer0 + n0;
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p1 = buffer1 + n1;
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if (! ROBUST_OUTPUT_STYLE (output_style)
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|| filevec[0].missing_newline == filevec[1].missing_newline)
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{
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end0 = p0; /* Addr of last char in file 0. */
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/* Get value of P0 at which we should stop scanning backward:
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this is when either P0 or P1 points just past the last char
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of the identical prefix. */
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beg0 = filevec[0].prefix_end + (n0 < n1 ? 0 : n0 - n1);
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/* Scan back until chars don't match or we reach that point. */
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while (p0 != beg0)
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if (*--p0 != *--p1)
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{
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/* Point at the first char of the matching suffix. */
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++p0, ++p1;
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beg0 = p0;
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break;
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}
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/* Are we at a line-beginning in both files? If not, add the rest of
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this line to the main body. Discard up to HORIZON_LINES lines from
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the identical suffix. Also, discard one extra line,
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because shift_boundaries may need it. */
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i = horizon_lines + !((buffer0 == p0 || p0[-1] == '\n')
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&&
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(buffer1 == p1 || p1[-1] == '\n'));
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while (i-- && p0 != end0)
|
||
while (*p0++ != '\n')
|
||
;
|
||
|
||
p1 += p0 - beg0;
|
||
}
|
||
|
||
/* Record the suffix. */
|
||
filevec[0].suffix_begin = p0;
|
||
filevec[1].suffix_begin = p1;
|
||
|
||
/* Calculate number of lines of prefix to save.
|
||
|
||
prefix_count == 0 means save the whole prefix;
|
||
we need this with for options like -D that output the whole file.
|
||
We also need it for options like -F that output some preceding line;
|
||
at least we will need to find the last few lines,
|
||
but since we don't know how many, it's easiest to find them all.
|
||
|
||
Otherwise, prefix_count != 0. Save just prefix_count lines at start
|
||
of the line buffer; they'll be moved to the proper location later.
|
||
Handle 1 more line than the context says (because we count 1 too many),
|
||
rounded up to the next power of 2 to speed index computation. */
|
||
|
||
if (no_diff_means_no_output && ! function_regexp_list)
|
||
{
|
||
for (prefix_count = 1; prefix_count < context + 1; prefix_count *= 2)
|
||
;
|
||
prefix_mask = prefix_count - 1;
|
||
alloc_lines0
|
||
= prefix_count
|
||
+ GUESS_LINES (0, 0, p0 - filevec[0].prefix_end)
|
||
+ context;
|
||
}
|
||
else
|
||
{
|
||
prefix_count = 0;
|
||
prefix_mask = ~0;
|
||
alloc_lines0 = GUESS_LINES (0, 0, n0);
|
||
}
|
||
|
||
lines = 0;
|
||
linbuf0 = (char const **) xmalloc (alloc_lines0 * sizeof (*linbuf0));
|
||
|
||
/* If the prefix is needed, find the prefix lines. */
|
||
if (! (no_diff_means_no_output
|
||
&& filevec[0].prefix_end == p0
|
||
&& filevec[1].prefix_end == p1))
|
||
{
|
||
p0 = buffer0;
|
||
end0 = filevec[0].prefix_end;
|
||
while (p0 != end0)
|
||
{
|
||
int l = lines++ & prefix_mask;
|
||
if (l == alloc_lines0)
|
||
linbuf0 = (char const **) xrealloc (linbuf0, (alloc_lines0 *= 2)
|
||
* sizeof(*linbuf0));
|
||
linbuf0[l] = p0;
|
||
while (*p0++ != '\n')
|
||
;
|
||
}
|
||
}
|
||
buffered_prefix = prefix_count && context < lines ? context : lines;
|
||
|
||
/* Allocate line buffer 1. */
|
||
tem = prefix_count ? filevec[1].suffix_begin - buffer1 : n1;
|
||
|
||
alloc_lines1
|
||
= (buffered_prefix
|
||
+ GUESS_LINES (lines, filevec[1].prefix_end - buffer1, tem)
|
||
+ context);
|
||
linbuf1 = (char const **) xmalloc (alloc_lines1 * sizeof (*linbuf1));
|
||
|
||
if (buffered_prefix != lines)
|
||
{
|
||
/* Rotate prefix lines to proper location. */
|
||
for (i = 0; i < buffered_prefix; i++)
|
||
linbuf1[i] = linbuf0[(lines - context + i) & prefix_mask];
|
||
for (i = 0; i < buffered_prefix; i++)
|
||
linbuf0[i] = linbuf1[i];
|
||
}
|
||
|
||
/* Initialize line buffer 1 from line buffer 0. */
|
||
for (i = 0; i < buffered_prefix; i++)
|
||
linbuf1[i] = linbuf0[i] - buffer0 + buffer1;
|
||
|
||
/* Record the line buffer, adjusted so that
|
||
linbuf*[0] points at the first differing line. */
|
||
filevec[0].linbuf = linbuf0 + buffered_prefix;
|
||
filevec[1].linbuf = linbuf1 + buffered_prefix;
|
||
filevec[0].linbuf_base = filevec[1].linbuf_base = - buffered_prefix;
|
||
filevec[0].alloc_lines = alloc_lines0 - buffered_prefix;
|
||
filevec[1].alloc_lines = alloc_lines1 - buffered_prefix;
|
||
filevec[0].prefix_lines = filevec[1].prefix_lines = lines;
|
||
}
|
||
|
||
/* Largest primes less than some power of two, for nbuckets. Values range
|
||
from useful to preposterous. If one of these numbers isn't prime
|
||
after all, don't blame it on me, blame it on primes (6) . . . */
|
||
static int const primes[] =
|
||
{
|
||
509,
|
||
1021,
|
||
2039,
|
||
4093,
|
||
8191,
|
||
16381,
|
||
32749,
|
||
#if 32767 < INT_MAX
|
||
65521,
|
||
131071,
|
||
262139,
|
||
524287,
|
||
1048573,
|
||
2097143,
|
||
4194301,
|
||
8388593,
|
||
16777213,
|
||
33554393,
|
||
67108859, /* Preposterously large . . . */
|
||
134217689,
|
||
268435399,
|
||
536870909,
|
||
1073741789,
|
||
2147483647,
|
||
#endif
|
||
0
|
||
};
|
||
|
||
/* Given a vector of two file_data objects, read the file associated
|
||
with each one, and build the table of equivalence classes.
|
||
Return 1 if either file appears to be a binary file.
|
||
If PRETEND_BINARY is nonzero, pretend they are binary regardless. */
|
||
|
||
int
|
||
read_files (filevec, pretend_binary)
|
||
struct file_data filevec[];
|
||
int pretend_binary;
|
||
{
|
||
int i;
|
||
int skip_test = always_text_flag | pretend_binary;
|
||
int appears_binary = pretend_binary | sip (&filevec[0], skip_test);
|
||
|
||
if (filevec[0].desc != filevec[1].desc)
|
||
appears_binary |= sip (&filevec[1], skip_test | appears_binary);
|
||
else
|
||
{
|
||
filevec[1].buffer = filevec[0].buffer;
|
||
filevec[1].bufsize = filevec[0].bufsize;
|
||
filevec[1].buffered_chars = filevec[0].buffered_chars;
|
||
}
|
||
if (appears_binary)
|
||
{
|
||
#if HAVE_SETMODE
|
||
setmode (filevec[0].desc, O_BINARY);
|
||
setmode (filevec[1].desc, O_BINARY);
|
||
#endif
|
||
return 1;
|
||
}
|
||
|
||
find_identical_ends (filevec);
|
||
|
||
equivs_alloc = filevec[0].alloc_lines + filevec[1].alloc_lines + 1;
|
||
equivs = (struct equivclass *) xmalloc (equivs_alloc * sizeof (struct equivclass));
|
||
/* Equivalence class 0 is permanently safe for lines that were not
|
||
hashed. Real equivalence classes start at 1. */
|
||
equivs_index = 1;
|
||
|
||
for (i = 0; primes[i] < equivs_alloc / 3; i++)
|
||
if (! primes[i])
|
||
abort ();
|
||
nbuckets = primes[i];
|
||
|
||
buckets = (int *) xmalloc ((nbuckets + 1) * sizeof (*buckets));
|
||
bzero (buckets++, (nbuckets + 1) * sizeof (*buckets));
|
||
|
||
for (i = 0; i < 2; i++)
|
||
find_and_hash_each_line (&filevec[i]);
|
||
|
||
filevec[0].equiv_max = filevec[1].equiv_max = equivs_index;
|
||
|
||
free (equivs);
|
||
free (buckets - 1);
|
||
|
||
return 0;
|
||
}
|