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fix memory-management problem in putenv

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Problem reported by Sergey Pinaev: free(oldbuffer) should be called
AFTER putenv(buffer).

Also, respond correctly to an (unlikely) putenv() failure.
This commit is contained in:
Matthew Flatt 2015-02-27 08:17:18 -07:00
parent f43096b123
commit 6cf28d55cd
1 changed files with 29 additions and 18 deletions
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47
racket/src/racket/src/string.c
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@ -2367,12 +2367,12 @@ static Scheme_Object *sch_getenv(int argc, Scheme_Object *argv[])
#ifndef DOS_FILE_SYSTEM #ifndef DOS_FILE_SYSTEM
static int sch_unix_putenv(const char *var, const char *val, const intptr_t varlen, const intptr_t vallen) { static int sch_unix_putenv(const char *var, const char *val, const intptr_t varlen, const intptr_t vallen) {
char *buffer; char *buffer;
intptr_t total_length; intptr_t total_length, r;
total_length = varlen + vallen + 2; total_length = varlen + vallen + 2;
if (val) { if (val) {
#ifdef MZ_PRECISE_GC #ifdef MZ_PRECISE_GC
/* Can't put moveable string into array. */ /* Can't put movable string into environ array */
buffer = malloc(total_length); buffer = malloc(total_length);
#else #else
buffer = (char *)scheme_malloc_atomic(total_length); buffer = (char *)scheme_malloc_atomic(total_length);
@ -2385,27 +2385,38 @@ static int sch_unix_putenv(const char *var, const char *val, const intptr_t varl
buffer = NULL; buffer = NULL;
} }
#ifdef MZ_PRECISE_GC
{
/* Free old, if in table: */
char *oldbuffer;
oldbuffer = (char *)putenv_str_table_get(var);
if (oldbuffer)
free(oldbuffer);
}
#endif
/* if precise the buffer needs to be remembered so it can be freed */
/* if not precise the buffer needs to be rooted so it doesn't get collected prematurely */
putenv_str_table_put_name(var, buffer);
if (buffer) if (buffer)
return putenv(buffer); r = putenv(buffer);
else { else {
/* on some platforms, unsetenv() returns void */ /* on some platforms, unsetenv() returns void */
unsetenv(var); unsetenv(var);
return 0; r = 0;
} }
if (!r) {
#ifdef MZ_PRECISE_GC
char *oldbuffer;
/* Will free old, if in table: */
oldbuffer = (char *)putenv_str_table_get(var);
#endif
/* If precise GC, the buffer needs to be remembered so it can be freed;
otherwise, the buffer needs to be referenced so it doesn't get GCed */
putenv_str_table_put_name(var, buffer);
#ifdef MZ_PRECISE_GC
if (oldbuffer)
free(oldbuffer);
#endif
} else {
#ifdef MZ_PRECISE_GC
if (buffer)
free(buffer);
#endif
}
return r;
} }
#endif #endif