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lib: Extract sys_popen()

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This was added by Jeremy with 3cf31a194f, do the (C) accordingly

sys_popen is a pretty isolated functionality, and I'd like to use it
soon without "includes.h", needed by "proto.h"

Except for one malloc->talloc this is supposed to be a 1:1 copy

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Michael Adam <obnox@samba.org>
This commit is contained in:
Volker Lendecke
2016-02-16 15:58:52 +01:00
committed by Michael Adam
parent 8338fe6ac8
commit 908df8ec13
6 changed files with 282 additions and 233 deletions
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231
source3/lib/system.c
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@ -966,237 +966,6 @@ int sys_setgroups(gid_t UNUSED(primary_gid), int setlen, gid_t *gidset)
#endif
}
/**************************************************************************
Extract a command into an arg list.
****************************************************************************/
static char **extract_args(TALLOC_CTX *mem_ctx, const char *command)
{
char *trunc_cmd;
char *saveptr;
char *ptr;
int argcl;
char **argl = NULL;
int i;
if (!(trunc_cmd = talloc_strdup(mem_ctx, command))) {
DEBUG(0, ("talloc failed\n"));
goto nomem;
}
if(!(ptr = strtok_r(trunc_cmd, " \t", &saveptr))) {
TALLOC_FREE(trunc_cmd);
errno = EINVAL;
return NULL;
}
/*
* Count the args.
*/
for( argcl = 1; ptr; ptr = strtok_r(NULL, " \t", &saveptr))
argcl++;
TALLOC_FREE(trunc_cmd);
if (!(argl = talloc_array(mem_ctx, char *, argcl + 1))) {
goto nomem;
}
/*
* Now do the extraction.
*/
if (!(trunc_cmd = talloc_strdup(mem_ctx, command))) {
goto nomem;
}
ptr = strtok_r(trunc_cmd, " \t", &saveptr);
i = 0;
if (!(argl[i++] = talloc_strdup(argl, ptr))) {
goto nomem;
}
while((ptr = strtok_r(NULL, " \t", &saveptr)) != NULL) {
if (!(argl[i++] = talloc_strdup(argl, ptr))) {
goto nomem;
}
}
argl[i++] = NULL;
TALLOC_FREE(trunc_cmd);
return argl;
nomem:
DEBUG(0, ("talloc failed\n"));
TALLOC_FREE(trunc_cmd);
TALLOC_FREE(argl);
errno = ENOMEM;
return NULL;
}
/**************************************************************************
Wrapper for popen. Safer as it doesn't search a path.
Modified from the glibc sources.
modified by tridge to return a file descriptor. We must kick our FILE* habit
****************************************************************************/
typedef struct _popen_list
{
int fd;
pid_t child_pid;
struct _popen_list *next;
} popen_list;
static popen_list *popen_chain;
int sys_popen(const char *command)
{
int parent_end, child_end;
int pipe_fds[2];
popen_list *entry = NULL;
char **argl = NULL;
int ret;
if (!*command) {
errno = EINVAL;
return -1;
}
ret = pipe(pipe_fds);
if (ret < 0) {
DEBUG(0, ("sys_popen: error opening pipe: %s\n",
strerror(errno)));
return -1;
}
parent_end = pipe_fds[0];
child_end = pipe_fds[1];
entry = SMB_MALLOC_P(popen_list);
if (entry == NULL) {
DEBUG(0, ("sys_popen: malloc failed\n"));
goto err_exit;
}
ZERO_STRUCTP(entry);
/*
* Extract the command and args into a NULL terminated array.
*/
argl = extract_args(NULL, command);
if (argl == NULL) {
DEBUG(0, ("sys_popen: extract_args() failed: %s\n", strerror(errno)));
goto err_exit;
}
entry->child_pid = fork();
if (entry->child_pid == -1) {
DEBUG(0, ("sys_popen: fork failed: %s\n", strerror(errno)));
goto err_exit;
}
if (entry->child_pid == 0) {
/*
* Child !
*/
int child_std_end = STDOUT_FILENO;
popen_list *p;
close(parent_end);
if (child_end != child_std_end) {
dup2 (child_end, child_std_end);
close (child_end);
}
/*
* POSIX.2: "popen() shall ensure that any streams from previous
* popen() calls that remain open in the parent process are closed
* in the new child process."
*/
for (p = popen_chain; p; p = p->next)
close(p->fd);
ret = execv(argl[0], argl);
if (ret == -1) {
DEBUG(0, ("sys_popen: ERROR executing command "
"'%s': %s\n", command, strerror(errno)));
}
_exit (127);
}
/*
* Parent.
*/
close (child_end);
TALLOC_FREE(argl);
/* Link into popen_chain. */
entry->next = popen_chain;
popen_chain = entry;
entry->fd = parent_end;
return entry->fd;
err_exit:
SAFE_FREE(entry);
TALLOC_FREE(argl);
close(pipe_fds[0]);
close(pipe_fds[1]);
return -1;
}
/**************************************************************************
Wrapper for pclose. Modified from the glibc sources.
****************************************************************************/
int sys_pclose(int fd)
{
int wstatus;
popen_list **ptr = &popen_chain;
popen_list *entry = NULL;
pid_t wait_pid;
int status = -1;
/* Unlink from popen_chain. */
for ( ; *ptr != NULL; ptr = &(*ptr)->next) {
if ((*ptr)->fd == fd) {
entry = *ptr;
*ptr = (*ptr)->next;
status = 0;
break;
}
}
if (status < 0 || close(entry->fd) < 0)
return -1;
/*
* As Samba is catching and eating child process
* exits we don't really care about the child exit
* code, a -1 with errno = ECHILD will do fine for us.
*/
do {
wait_pid = waitpid (entry->child_pid, &wstatus, 0);
} while (wait_pid == -1 && errno == EINTR);
SAFE_FREE(entry);
if (wait_pid == -1)
return -1;
return wstatus;
}
/****************************************************************************
Return the major devicenumber for UNIX extensions.
****************************************************************************/