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sh: Constify internal representation in expand.c.

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Forbid (temporary or permanent) modifications of the strings in NARG nodes
during expansion.

Tilde expansion now needs to copy the username for the terminating '\0'.
This commit is contained in:
Jilles Tjoelker 2016-01-24 22:26:25 +00:00
parent 18a2ccd22d
commit 52d5897d50
1 changed files with 28 additions and 22 deletions
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50
bin/sh/expand.c
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@ -91,13 +91,13 @@ struct worddest {
static char *expdest; /* output of current string */ static char *expdest; /* output of current string */
static struct nodelist *argbackq; /* list of back quote expressions */ static struct nodelist *argbackq; /* list of back quote expressions */
static char *argstr(char *, int, struct worddest *); static const char *argstr(const char *, int, struct worddest *);
static char *exptilde(char *, int); static const char *exptilde(const char *, int);
static char *expari(char *, int, struct worddest *); static const char *expari(const char *, int, struct worddest *);
static void expbackq(union node *, int, int, struct worddest *); static void expbackq(union node *, int, int, struct worddest *);
static void subevalvar_trim(char *, int, int, int); static void subevalvar_trim(const char *, int, int, int);
static int subevalvar_misc(char *, const char *, int, int, int); static int subevalvar_misc(const char *, const char *, int, int, int);
static char *evalvar(char *, int, struct worddest *); static const char *evalvar(const char *, int, struct worddest *);
static int varisset(const char *, int); static int varisset(const char *, int);
static void strtodest(const char *, int, int, int, struct worddest *); static void strtodest(const char *, int, int, int, struct worddest *);
static void reprocess(int, int, int, int, struct worddest *); static void reprocess(int, int, int, int, struct worddest *);
@ -262,8 +262,8 @@ expandarg(union node *arg, struct arglist *arglist, int flag)
* *
* If EXP_SPLIT is set, dst receives any complete words produced. * If EXP_SPLIT is set, dst receives any complete words produced.
*/ */
static char * static const char *
argstr(char *p, int flag, struct worddest *dst) argstr(const char *p, int flag, struct worddest *dst)
{ {
char c; char c;
int quotes = flag & (EXP_GLOB | EXP_CASE); /* do CTLESC */ int quotes = flag & (EXP_GLOB | EXP_CASE); /* do CTLESC */
@ -352,12 +352,15 @@ argstr(char *p, int flag, struct worddest *dst)
* Perform tilde expansion, placing the result in the stack string and * Perform tilde expansion, placing the result in the stack string and
* returning the next position in the input string to process. * returning the next position in the input string to process.
*/ */
static char * static const char *
exptilde(char *p, int flag) exptilde(const char *p, int flag)
{ {
char c, *startp = p; char c;
const char *startp = p;
const char *user;
struct passwd *pw; struct passwd *pw;
char *home; char *home;
int len;
for (;;) { for (;;) {
c = *p; c = *p;
@ -377,14 +380,17 @@ exptilde(char *p, int flag)
case '\0': case '\0':
case '/': case '/':
case CTLENDVAR: case CTLENDVAR:
*p = '\0'; len = p - startp - 1;
if (*(startp+1) == '\0') { STPUTBIN(startp + 1, len, expdest);
STACKSTRNUL(expdest);
user = expdest - len;
if (*user == '\0') {
home = lookupvar("HOME"); home = lookupvar("HOME");
} else { } else {
pw = getpwnam(startp+1); pw = getpwnam(user);
home = pw != NULL ? pw->pw_dir : NULL; home = pw != NULL ? pw->pw_dir : NULL;
} }
*p = c; STADJUST(-len, expdest);
if (home == NULL || *home == '\0') if (home == NULL || *home == '\0')
return (startp); return (startp);
strtodest(home, flag, VSNORMAL, 1, NULL); strtodest(home, flag, VSNORMAL, 1, NULL);
@ -398,8 +404,8 @@ exptilde(char *p, int flag)
/* /*
* Expand arithmetic expression. * Expand arithmetic expression.
*/ */
static char * static const char *
expari(char *p, int flag, struct worddest *dst) expari(const char *p, int flag, struct worddest *dst)
{ {
char *q, *start; char *q, *start;
arith_t result; arith_t result;
@ -532,7 +538,7 @@ recordleft(const char *str, const char *loc, char *startp)
} }
static void static void
subevalvar_trim(char *p, int strloc, int subtype, int startloc) subevalvar_trim(const char *p, int strloc, int subtype, int startloc)
{ {
char *startp; char *startp;
char *loc = NULL; char *loc = NULL;
@ -606,7 +612,7 @@ subevalvar_trim(char *p, int strloc, int subtype, int startloc)
static int static int
subevalvar_misc(char *p, const char *var, int subtype, int startloc, subevalvar_misc(const char *p, const char *var, int subtype, int startloc,
int varflags) int varflags)
{ {
char *startp; char *startp;
@ -645,12 +651,12 @@ subevalvar_misc(char *p, const char *var, int subtype, int startloc,
* input string. * input string.
*/ */
static char * static const char *
evalvar(char *p, int flag, struct worddest *dst) evalvar(const char *p, int flag, struct worddest *dst)
{ {
int subtype; int subtype;
int varflags; int varflags;
char *var; const char *var;
const char *val; const char *val;
int patloc; int patloc;
int c; int c;