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scandir(3) previously used st_size to obtain an initial estimate

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of the array length needed to store all the directory entries.
Although BSD has historically guaranteed that st_size is the size
of the directory file, POSIX does not, and more to the point, some
recent filesystems such as ZFS use st_size to mean something else.

The fix is to not stat the directory at all, set the initial
array size to 32 entries, and realloc it in powers of 2 if that
proves insufficient.

PR:	113668
This commit is contained in:
David Schultz 2008-03-16 19:08:53 +00:00
parent 45fa2c8a87
commit 18798c64f0
1 changed files with 3 additions and 13 deletions
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16
lib/libc/gen/scandir.c
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@ -41,8 +41,6 @@ __FBSDID("$FreeBSD$");
*/
#include "namespace.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <stdlib.h>
#include <string.h>
@ -68,20 +66,13 @@ scandir(dirname, namelist, select, dcomp)
{
struct dirent *d, *p, **names = NULL;
size_t nitems = 0;
struct stat stb;
long arraysz;
DIR *dirp;
if ((dirp = opendir(dirname)) == NULL)
return(-1);
if (_fstat(dirp->dd_fd, &stb) < 0)
goto fail;
/*
* estimate the array size by taking the size of the directory file
* and dividing it by a multiple of the minimum size entry.
*/
arraysz = (stb.st_size / 24);
arraysz = 32; /* initial estimate of the array size */
names = (struct dirent **)malloc(arraysz * sizeof(struct dirent *));
if (names == NULL)
goto fail;
@ -105,17 +96,16 @@ scandir(dirname, namelist, select, dcomp)
* realloc the maximum size.
*/
if (nitems >= arraysz) {
const int inc = 10; /* increase by this much */
struct dirent **names2;
names2 = (struct dirent **)realloc((char *)names,
(arraysz + inc) * sizeof(struct dirent *));
(arraysz * 2) * sizeof(struct dirent *));
if (names2 == NULL) {
free(p);
goto fail;
}
names = names2;
arraysz += inc;
arraysz *= 2;
}
names[nitems++] = p;
}