From a32179878e8e439948a4a6385515a0aea7a61592 Mon Sep 17 00:00:00 2001
From: Dmitry Rozhkov <dmitry.rozhkov@intel.com>
Date: Fri, 29 Jan 2016 17:48:46 +0200
Subject: [PATCH] Add system_argv() helper for safer calls to system utilities

Often file names contain special characters like hashes or
whitespaces and that makes escaping a difficult task when using
system(). Thus add a new helper system_argv() that is based
on execvp() syscall and doesn't require escaping.

Signed-off-by: Dmitry Rozhkov <dmitry.rozhkov@intel.com>

Upstream-Status: Backport [v2.54+]

---
 include/swupd.h |  1 +
 src/fullfiles.c |  6 ++----
 src/helpers.c   | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/include/swupd.h b/include/swupd.h
index 522ac2e..ad4b967 100644
--- a/include/swupd.h
+++ b/include/swupd.h
@@ -228,6 +228,7 @@ extern FILE * fopen_exclusive(const char *filename); /* no mode, opens for write
 extern void dump_file_info(struct file *file);
 extern void string_or_die(char **strp, const char *fmt, ...);
 extern void print_elapsed_time(struct timeval *previous_time, struct timeval *current_time);
+extern int system_argv(char *const argv[]);

 extern bool signature_initialize(void);
 extern void signature_terminate(void);
diff --git a/src/fullfiles.c b/src/fullfiles.c
index 1bb581e..fa78293 100644
--- a/src/fullfiles.c
+++ b/src/fullfiles.c
@@ -138,12 +138,10 @@ static void create_fullfile(struct file *file)
 		string_or_die(&tempfile, "%s/%s", empty, file->hash);
 		if (link(origin, tempfile) < 0) {
 			LOG(NULL, "hardlink failed", "%s due to %s (%s -> %s)", file->filename, strerror(errno), origin, tempfile);
-			string_or_die(&tarcommand, "cp -a %s %s", origin, tempfile);
-			if (system(tarcommand) != 0) {
-				LOG(NULL, "Failed to run command:", "%s", tarcommand);
+			char *const argv[] = {"cp", "-a", origin, tempfile, NULL};
+			if (system_argv(argv) != 0) {
 				assert(0);
 			}
-			free(tarcommand);
 		}

 		/* step 2a: tar it with each compression type  */
diff --git a/src/helpers.c b/src/helpers.c
index 65acffd..5884b51 100644
--- a/src/helpers.c
+++ b/src/helpers.c
@@ -29,6 +29,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/time.h>
+#include <sys/wait.h>
 #include <fcntl.h>
 #include <errno.h>

@@ -124,3 +125,65 @@ void print_elapsed_time(struct timeval *previous_time, struct timeval *current_t

 	free(elapsed);
 }
+
+void concat_str_array(char **output, char *const argv[])
+{
+	int size = 0;
+
+	for (int i = 0; argv[i]; i++) {
+		size += strlen(argv[i]) + 1;
+	}
+
+	*output = malloc(size + 1);
+	if (!*output) {
+		LOG(NULL, "Failed to allocate", "%i bytes", size);
+		assert(0);
+	}
+	strcpy(*output, "");
+	for (int i = 0; argv[i]; i++) {
+		strcat(*output, argv[i]);
+		strcat(*output, " ");
+	}
+}
+
+int system_argv(char *const argv[])
+{
+	int child_exit_status;
+	pid_t pid;
+	int status;
+
+	pid = fork();
+
+	if (pid == 0) { /* child */
+		execvp(*argv, argv);
+		LOG(NULL, "This line must not be reached", "");
+		assert(0);
+	} else if (pid < 0) {
+		LOG(NULL, "Failed to fork a child process", "");
+		assert(0);
+	} else {
+		pid_t ws = waitpid(pid, &child_exit_status, 0);
+
+		if (ws == -1) {
+			LOG(NULL, "Failed to wait for child process", "");
+			assert(0);
+		}
+
+		if (WIFEXITED(child_exit_status)) {
+			status = WEXITSTATUS(child_exit_status);
+		} else {
+			LOG(NULL, "Child process didn't exit", "");
+			assert(0);
+		}
+
+		if (status != 0) {
+			char* cmdline = NULL;
+
+			concat_str_array(&cmdline, argv);
+			LOG(NULL, "Failed to run command:", "%s", cmdline);
+			free(cmdline);
+		}
+
+		return status;
+	}
+}
--
2.5.0