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src/useradd.c: Add fmkstemp() to fix file-descriptor leak

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This function creates a temporary file, and returns a FILE pointer to
it.  This avoids dealing with both a file descriptor and a FILE pointer,
and correctly deallocating the resources on error.

The code before this patch was leaking the file descriptor if fdopen(3)
failed.

Reviewed-by: Iker Pedrosa <ipedrosa@redhat.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
This commit is contained in:
Alejandro Colomar 2024-05-17 13:40:58 +02:00
parent a74c4b6ae1
commit e7d1508e07
1 changed files with 24 additions and 10 deletions
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34
src/useradd.c
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@ -238,6 +238,9 @@ static void create_home (void);
static void create_mail (void);
static void check_uid_range(int rflg, uid_t user_id);
static FILE *fmkstemp(char *template);
/*
* fail_exit - undo as much as possible
*/
@ -524,7 +527,6 @@ static void show_defaults (void)
*/
static int set_defaults (void)
{
int ofd;
int ret = -1;
bool out_group = false;
bool out_groups = false;
@ -582,15 +584,7 @@ static int set_defaults (void)
/*
* Create a temporary file to copy the new output to.
*/
ofd = mkstemp (new_file);
if (-1 == ofd) {
fprintf (stderr,
_("%s: cannot create new defaults file\n"),
Prog);
goto err_free_def;
}
ofp = fdopen (ofd, "w");
ofp = fmkstemp(new_file);
if (NULL == ofp) {
fprintf (stderr,
_("%s: cannot open new defaults file\n"),
@ -2752,3 +2746,23 @@ int main (int argc, char **argv)
return E_SUCCESS;
}
static FILE *
fmkstemp(char *template)
{
int fd;
FILE *fp;
fd = mkstemp(template);
if (fd == -1)
return NULL;
fp = fdopen(fd, "w");
if (fp == NULL) {
close(fd);
unlink(template);
return NULL;
}
return fp;
}