[klibc] [PATCH v2 3/4] kinit: Add run_scripts()

[Mike Waychison]

This patch implements support for executing files present in drop
directories.  This is implemented by a new function called run_scripts,
which takes the name of the base drop-directory to search for scripts.

It is implemented by simply doing a single-depth search for files
present in the directory using scandir().  It then will synchronously
execute each file in order.  Failure to execute anything that looks like
a file is treated as a fatal error, which should be easy to catch as
these directories are essentially configuration directories and failure
to execute should be immediately visible to developers.

Execution is implemented as a simple fork/exec, passing all the command
line flags in as the arguments to the executed script/binary.

Signed-off-by: Mike Waychison <mikew at google.com>
---
 usr/kinit/Kbuild        |    2 -
 usr/kinit/kinit.h       |    2 +
 usr/kinit/run_scripts.c |  110 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 113 insertions(+), 1 deletions(-)
 create mode 100644 usr/kinit/run_scripts.c

diff --git a/usr/kinit/Kbuild b/usr/kinit/Kbuild
index ff1d449..b743b87 100644
--- a/usr/kinit/Kbuild
+++ b/usr/kinit/Kbuild
@@ -8,7 +8,7 @@ lib-y   := name_to_dev.o devname.o getarg.o
 kinit-y  := lib.a
 
 kinit-y  += kinit.o do_mounts.o ramdisk_load.o initrd.o
-kinit-y  += getintfile.o readfile.o xpio.o
+kinit-y  += getintfile.o readfile.o xpio.o run_scripts.o
 kinit-y  += do_mounts_md.o do_mounts_mtd.o nfsroot.o
 
 kinit-y  += ipconfig/
diff --git a/usr/kinit/kinit.h b/usr/kinit/kinit.h
index c2e67b7..808deee 100644
--- a/usr/kinit/kinit.h
+++ b/usr/kinit/kinit.h
@@ -65,4 +65,6 @@ static inline void dump_args(int argc, char *argv[])
 }
 #endif
 
+void run_scripts(const char *basepath, int cmdc, char **cmdv);
+
 #endif				/* KINIT_H */
diff --git a/usr/kinit/run_scripts.c b/usr/kinit/run_scripts.c
new file mode 100644
index 0000000..4609b39
--- /dev/null
+++ b/usr/kinit/run_scripts.c
@@ -0,0 +1,110 @@
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <dirent.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "kinit.h"
+
+static int is_file(const struct dirent *dirent)
+{
+	return (dirent->d_type == DT_REG);
+}
+
+static void run_script(const char *basepath, const char *filename,
+		       int cmdc, char **cmdv)
+{
+	char *fullpath;
+	char **args;
+	pid_t pid;
+	int status;
+	int ret;
+	int i;
+
+	/* Figure out fullpath */
+	fullpath = malloc(strlen(basepath) + strlen(filename) + 2);
+	if (!fullpath) {
+		fprintf(stderr, "Ran out of memory!\n");
+		exit(1);
+	}
+	sprintf(fullpath, "%s/%s", basepath, filename);
+
+	/* Prepare args for call */
+	args = malloc(sizeof(*args) * (cmdc + 2)); /* NULL + ARGV[0} */
+	if (!args) {
+		fprintf(stderr, "Ran out of memory!\n");
+		free(fullpath);
+		exit(1);
+	}
+	args[0] = fullpath;
+	for (i = 0; i < cmdc; i++)
+		args[i + 1] = cmdv[i];
+	args[cmdc + 1] = NULL;
+
+	/* Run the child */
+	pid = fork();
+	if (pid == -1) {
+		fprintf(stderr, "Failed to fork in run_scripts(%s)\n",
+			basepath);
+		exit(1);
+	}
+	if (pid == 0) {
+		/* Child */
+		execv(fullpath, args);
+		fprintf(stderr, "Failed to exec %s: %s\n", fullpath,
+			strerror(errno));
+		exit(1);
+	}
+
+	/* Parent */
+	while (1) {
+		ret = waitpid(pid, &status, 0);
+		if (ret == pid)
+			break;
+		if (ret == -1 && errno == EINTR)
+			continue;
+		fprintf(stderr, "failed to wait on child: ret=%d errno=%d\n",
+			ret, errno);
+		exit(1);
+	}
+
+	if (WIFEXITED(status)) {
+		if (WEXITSTATUS(status) != 0)
+			fprintf(stderr, "%s exited with status: %d\n",
+				fullpath, WEXITSTATUS(status));
+	} else if (WIFSIGNALED(status)) {
+		fprintf(stderr, "%s terminated by signal %d\n",
+			fullpath, WTERMSIG(status));
+	} else {
+		fprintf(stderr, "Failed to understand status code 0x%x\n",
+			status);
+	}
+
+	free(args);
+	free(fullpath);
+}
+
+void run_scripts(const char *basepath, int cmdc, char **cmdv)
+{
+	struct dirent **namelist;
+	int i;
+	int count;
+
+	count = scandir(basepath, &namelist, is_file, alphasort);
+	if (count < 0) {
+		if (errno == ENOENT)
+			return;
+		fprintf(stderr, "WARNING: could not run_scripts(%s): %s\n",
+			basepath, strerror(errno));
+		return;
+	}
+
+	for (i = 0; i < count; i++) {
+		run_script(basepath, namelist[i]->d_name, cmdc, cmdv);
+		free(namelist[i]);
+	}
+	free(namelist);
+}