---
systemvp should pretty much be a drop-in replacement for system with
the exception that it takes an argv array and uses exec. If anybody
wants to play with it to stress test it a little, I have
a self-contained copy and test program at:
https://github.com/andrewgregory/snippets/blob/systemv/c/systemv.c
TODO:
* update docs
* fix debug logging
* should the command be run with PATH lookup (execv vs execvp)?
* Is the use of mmap with MAP_ANONYMOUS okay? MAP_ANONYMOUS is
not POSIX but "most systems also support MAP_ANONYMOUS (or its
synonym MAP_ANON)" (mmap(2)).
* should we reset signals prior to exec'ing like we do with
hooks/scripts?
src/pacman/conf.c | 95 ++++++++++++++++++++++++++++++++++++++---------
src/pacman/conf.h | 2 +
2 files changed, 80 insertions(+), 17 deletions(-)
diff --git a/src/pacman/conf.c b/src/pacman/conf.c
index 2d8518c4..faf446dc 100644
--- a/src/pacman/conf.c
+++ b/src/pacman/conf.c
@@ -26,9 +26,11 @@
#include <stdlib.h>
#include <stdio.h>
#include <string.h> /* strdup */
+#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/utsname.h> /* uname */
+#include <sys/wait.h>
#include <unistd.h>
/* pacman */
@@ -153,6 +155,7 @@ int config_free(config_t *oldconfig)
free(oldconfig->print_format);
free(oldconfig->arch);
free(oldconfig);
+ _alpm_wordsplit_free(oldconfig->xfercommand_argv);
return 0;
}
@@ -201,18 +204,59 @@ static char *get_tempfile(const char *path, const char
*filename)
return tempfile;
}
+static int systemvp(const char *file, char *const argv[])
+{
+ int pid, *err;
+
+ err = mmap(NULL, sizeof(*err), PROT_READ | PROT_WRITE,
+ MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+ if(err == NULL) {
+ return -1;
+ }
+
+ pid = fork();
+ if(pid == -1) {
+ /* error */
+ munmap(err, sizeof(*err));
+ return -1;
+ } else if(pid == 0) {
+ /* child */
+ *err = 0;
+ execvp(file, argv);
+ *err = errno;
+ munmap(err, sizeof(*err));
+ _Exit(1);
+ } else {
+ /* parent */
+ int status;
+ while(waitpid(pid, &status, 0) == -1) {
+ if(errno != EINTR) {
+ munmap(err, sizeof(*err));
+ return -1;
+ }
+ }
+ if(*err != 0) {
+ errno = *err;
+ status = -1;
+ }
+ munmap(err, sizeof(*err));
+ return status;
+ }
+}
+
/** External fetch callback */
static int download_with_xfercommand(const char *url, const char *localpath,
int force)
{
int ret = 0, retval;
int usepart = 0;
- int cwdfd;
+ int cwdfd = -1;
struct stat st;
- char *parsedcmd, *tempcmd;
char *destfile, *tempfile, *filename;
+ const char **argv;
+ size_t i;
- if(!config->xfercommand) {
+ if(!config->xfercommand_argv) {
return -1;
}
@@ -230,17 +274,20 @@ static int download_with_xfercommand(const char *url,
const char *localpath,
unlink(destfile);
}
- tempcmd = strdup(config->xfercommand);
- /* replace all occurrences of %o with fn.part */
- if(strstr(tempcmd, "%o")) {
- usepart = 1;
- parsedcmd = strreplace(tempcmd, "%o", tempfile);
- free(tempcmd);
- tempcmd = parsedcmd;
+ if((argv = calloc(config->xfercommand_argc + 1, sizeof(char*))) ==
NULL) {
+ pm_printf(ALPM_LOG_ERROR, _("could not get current working
directory\n"));
+ goto cleanup;
+ }
+
+ for(i = 0; i <= config->xfercommand_argc; i++) {
+ const char *val = config->xfercommand_argv[i];
+ if(val && strcmp(val, "%o") == 0) {
+ val = tempfile;
+ } else if(val && strcmp(val, "%u") == 0) {
+ val = url;
+ }
+ argv[i] = val;
}
- /* replace all occurrences of %u with the download URL */
- parsedcmd = strreplace(tempcmd, "%u", url);
- free(tempcmd);
/* save the cwd so we can restore it later */
do {
@@ -256,9 +303,13 @@ static int download_with_xfercommand(const char *url,
const char *localpath,
ret = -1;
goto cleanup;
}
- /* execute the parsed command via /bin/sh -c */
- pm_printf(ALPM_LOG_DEBUG, "running command: %s\n", parsedcmd);
- retval = system(parsedcmd);
+
+ printf("running command: %s", config->xfercommand_argv[0]);
+ for(i = 1; argv[i]; i++) {
+ printf(" '%s'", argv[i]);
+ }
+ printf("\n");
+ retval = systemvp(argv[0], (char**)argv);
if(retval == -1) {
pm_printf(ALPM_LOG_WARNING, _("running XferCommand: fork
failed!\n"));
@@ -296,7 +347,6 @@ cleanup:
}
free(destfile);
free(tempfile);
- free(parsedcmd);
return ret;
}
@@ -544,6 +594,17 @@ static int _parse_options(const char *key, char *value,
pm_printf(ALPM_LOG_DEBUG, "config: logfile:
%s\n", value);
}
} else if(strcmp(key, "XferCommand") == 0) {
+ char **c;
+ if((config->xfercommand_argv = _alpm_wordsplit(value))
== NULL) {
+ pm_printf(ALPM_LOG_WARNING,
+ _("config file %s, line %d:
invalid value for '%s' : '%s'\n"),
+ file, linenum, "XferCommand",
value);
+ return 1;
+ }
+ config->xfercommand_argc = 0;
+ for(c = config->xfercommand_argv; *c; c++) {
+ config->xfercommand_argc++;
+ }
config->xfercommand = strdup(value);
pm_printf(ALPM_LOG_DEBUG, "config: xfercommand: %s\n",
value);
} else if(strcmp(key, "CleanMethod") == 0) {
diff --git a/src/pacman/conf.h b/src/pacman/conf.h
index f45ed436..47df979d 100644
--- a/src/pacman/conf.h
+++ b/src/pacman/conf.h
@@ -125,6 +125,8 @@ typedef struct __config_t {
alpm_list_t *noextract;
alpm_list_t *overwrite_files;
char *xfercommand;
+ char **xfercommand_argv;
+ size_t xfercommand_argc;
/* our connection to libalpm */
alpm_handle_t *handle;
--
2.21.0
