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Diffstat (limited to 'libnetdata/popen/popen.c')
-rw-r--r--libnetdata/popen/popen.c118
1 files changed, 84 insertions, 34 deletions
diff --git a/libnetdata/popen/popen.c b/libnetdata/popen/popen.c
index 1c4ae64d6..c0135cf40 100644
--- a/libnetdata/popen/popen.c
+++ b/libnetdata/popen/popen.c
@@ -78,8 +78,16 @@ static void myp_del(pid_t pid) {
#define PIPE_READ 0
#define PIPE_WRITE 1
-static inline FILE *custom_popene(const char *command, volatile pid_t *pidptr, char **env) {
- FILE *fp;
+/* custom_popene flag definitions */
+#define FLAG_CREATE_PIPE 1 // Create a pipe like popen() when set, otherwise set stdout to /dev/null
+#define FLAG_CLOSE_FD 2 // Close all file descriptors other than STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO
+
+/*
+ * Returns -1 on failure, 0 on success. When FLAG_CREATE_PIPE is set, on success set the FILE *fp pointer.
+ */
+static inline int custom_popene(const char *command, volatile pid_t *pidptr, char **env, uint8_t flags, FILE **fpp) {
+ FILE *fp = NULL;
+ int ret = 0; // success by default
int pipefd[2], error;
pid_t pid;
char *const spawn_argv[] = {
@@ -91,23 +99,36 @@ static inline FILE *custom_popene(const char *command, volatile pid_t *pidptr, c
posix_spawnattr_t attr;
posix_spawn_file_actions_t fa;
- if (pipe(pipefd) == -1)
- return NULL;
- if ((fp = fdopen(pipefd[PIPE_READ], "r")) == NULL) {
- goto error_after_pipe;
+ if (flags & FLAG_CREATE_PIPE) {
+ if (pipe(pipefd) == -1)
+ return -1;
+ if ((fp = fdopen(pipefd[PIPE_READ], "r")) == NULL) {
+ goto error_after_pipe;
+ }
}
- // Mark all files to be closed by the exec() stage of posix_spawn()
- int i;
- for (i = (int) (sysconf(_SC_OPEN_MAX) - 1); i >= 0; i--)
- if(i != STDIN_FILENO && i != STDERR_FILENO)
- (void)fcntl(i, F_SETFD, FD_CLOEXEC);
+ if (flags & FLAG_CLOSE_FD) {
+ // Mark all files to be closed by the exec() stage of posix_spawn()
+ int i;
+ for (i = (int) (sysconf(_SC_OPEN_MAX) - 1); i >= 0; i--) {
+ if (i != STDIN_FILENO && i != STDERR_FILENO)
+ (void) fcntl(i, F_SETFD, FD_CLOEXEC);
+ }
+ }
if (!posix_spawn_file_actions_init(&fa)) {
- // move the pipe to stdout in the child
- if (posix_spawn_file_actions_adddup2(&fa, pipefd[PIPE_WRITE], STDOUT_FILENO)) {
- error("posix_spawn_file_actions_adddup2() failed");
- goto error_after_posix_spawn_file_actions_init;
+ if (flags & FLAG_CREATE_PIPE) {
+ // move the pipe to stdout in the child
+ if (posix_spawn_file_actions_adddup2(&fa, pipefd[PIPE_WRITE], STDOUT_FILENO)) {
+ error("posix_spawn_file_actions_adddup2() failed");
+ goto error_after_posix_spawn_file_actions_init;
+ }
+ } else {
+ // set stdout to /dev/null
+ if (posix_spawn_file_actions_addopen(&fa, STDOUT_FILENO, "/dev/null", O_WRONLY, 0)) {
+ error("posix_spawn_file_actions_addopen() failed");
+ // this is not a fatal error
+ }
}
} else {
error("posix_spawn_file_actions_init() failed.");
@@ -136,10 +157,16 @@ static inline FILE *custom_popene(const char *command, volatile pid_t *pidptr, c
} else {
myp_add_unlock();
error("Failed to spawn command: '%s' from parent pid %d.", command, getpid());
- fclose(fp);
- fp = NULL;
+ if (flags & FLAG_CREATE_PIPE) {
+ fclose(fp);
+ }
+ ret = -1;
+ }
+ if (flags & FLAG_CREATE_PIPE) {
+ close(pipefd[PIPE_WRITE]);
+ if (0 == ret) // on success set FILE * pointer
+ *fpp = fp;
}
- close(pipefd[PIPE_WRITE]);
if (!error) {
// posix_spawnattr_init() succeeded
@@ -149,19 +176,21 @@ static inline FILE *custom_popene(const char *command, volatile pid_t *pidptr, c
if (posix_spawn_file_actions_destroy(&fa))
error("posix_spawn_file_actions_destroy");
- return fp;
+ return ret;
error_after_posix_spawn_file_actions_init:
if (posix_spawn_file_actions_destroy(&fa))
error("posix_spawn_file_actions_destroy");
error_after_pipe:
- if (fp)
- fclose(fp);
- else
- close(pipefd[PIPE_READ]);
+ if (flags & FLAG_CREATE_PIPE) {
+ if (fp)
+ fclose(fp);
+ else
+ close(pipefd[PIPE_READ]);
- close(pipefd[PIPE_WRITE]);
- return NULL;
+ close(pipefd[PIPE_WRITE]);
+ }
+ return -1;
}
// See man environ
@@ -222,26 +251,37 @@ int myp_reap(pid_t pid) {
}
FILE *mypopen(const char *command, volatile pid_t *pidptr) {
- return custom_popene(command, pidptr, environ);
+ FILE *fp = NULL;
+ (void)custom_popene(command, pidptr, environ, FLAG_CREATE_PIPE | FLAG_CLOSE_FD, &fp);
+ return fp;
}
FILE *mypopene(const char *command, volatile pid_t *pidptr, char **env) {
- return custom_popene(command, pidptr, env);
+ FILE *fp = NULL;
+ (void)custom_popene(command, pidptr, env, FLAG_CREATE_PIPE | FLAG_CLOSE_FD, &fp);
+ return fp;
+}
+
+// returns 0 on success, -1 on failure
+int netdata_spawn(const char *command, volatile pid_t *pidptr) {
+ return custom_popene(command, pidptr, environ, 0, NULL);
}
-int mypclose(FILE *fp, pid_t pid) {
+int custom_pclose(FILE *fp, pid_t pid) {
int ret;
siginfo_t info;
debug(D_EXIT, "Request to mypclose() on pid %d", pid);
- // close the pipe fd
- // this is required in musl
- // without it the childs do not exit
- close(fileno(fp));
+ if (fp) {
+ // close the pipe fd
+ // this is required in musl
+ // without it the childs do not exit
+ close(fileno(fp));
- // close the pipe file pointer
- fclose(fp);
+ // close the pipe file pointer
+ fclose(fp);
+ }
errno = 0;
@@ -285,3 +325,13 @@ int mypclose(FILE *fp, pid_t pid) {
return 0;
}
+
+int mypclose(FILE *fp, pid_t pid)
+{
+ return custom_pclose(fp, pid);
+}
+
+int netdata_spawn_waitpid(pid_t pid)
+{
+ return custom_pclose(NULL, pid);
+} \ No newline at end of file