Factorize child process execution code

1 files changed, 66 insertions, 58 deletions

diff --git a/src/main.c b/src/main.c
index 1107624..c33ea36 100644
--- a/src/main.c
+++ b/src/main.c
@@ -97,6 +97,40 @@ static void assert_db_exists(void)
 	exit(EXIT_FAILURE);
 }
 
+/* Execute command in a child process, then wait for the child to exit before
+ * returning. If any error occurs, including in the child process, then if EXIT
+ * is non-zero, exit, else return -1. Return 0 on success. */
+static int ftag_execvp(char *const *cmd, int can_exit)
+{
+	int status = 0;
+	int rc = fork();
+	if (rc == 0) {
+		execvp(cmd[0], cmd);
+		fprintf(stderr, "exec: %s: ", cmd[0]);
+		perror("");
+	}
+	else if (rc > 0) {
+		int status;
+		wait(&status);
+		if (!(WIFEXITED(status) && WEXITSTATUS(status) == 0)) {
+			fprintf(stderr,
+				"ftag: child process exited abnormally\n");
+			if (can_exit)
+				exit(EXIT_FAILURE);
+			else
+				status = -1;
+		}
+	}
+	else {
+		perror("fork");
+		if (can_exit)
+			exit(EXIT_FAILURE);
+		else
+			status = -1;
+	}
+	return status;
+}
+
 /* Copy the file whose path is IN at path OUT. OUT is created or overwritten if
  * needed. */
 static void copy_file(const char *in, const char *out)
@@ -138,39 +172,25 @@ static void copy_file(const char *in, const char *out)
 static void
 copy_file_with_encryption(const char *in, const char *out, enum encrypt encrypt)
 {
-	int rc = fork();
 	char *crypt_param;
 	assert(encrypt == ENCRYPT || encrypt == DECRYPT);
 	if (encrypt == ENCRYPT)
 		crypt_param = "--encrypt";
 	else
 		crypt_param = "--decrypt";
-	if (rc == 0) {
-		execlp("gpg",
-		       "gpg",
-		       "--output", out,
-		       "--yes", /* do not ask for overwriting files, maybe
-				 * dangerous if GPG asks security questions */
-		       crypt_param, in,
-		       NULL);
-		fprintf(stderr, "exec: gpg:");
-		perror("");
-		exit(EXIT_FAILURE);
-	}
-	else if (rc > 0) {
-		int status;
-		wait(&status);
-		if (!(WIFEXITED(status) && WEXITSTATUS(status) == 0)) {
-			fprintf(stderr,
-				"ftag file add: "
-				"child process exited abnormally\n");
-			exit(EXIT_FAILURE);
-		}
-	}
-	else {
-		perror("fork");
-		exit(EXIT_FAILURE);
-	}
+	/* use dups to suppress "discards const qualifier" warnings */
+	char *in_dup = strdup(in);
+	char *out_dup = strdup(out);
+	char *cmd[] = {
+		"gpg",
+		"--output", out_dup,
+		"--yes",
+		crypt_param, in_dup,
+		NULL
+	};
+	ftag_execvp(cmd, 1);
+	free(in_dup);
+	free(out_dup);
 }
 
 /* Prompt the user for yes or no (default is yes). Before calling, a prompt
@@ -485,37 +505,25 @@ static void ftag_export(int argc, char **argv)
 	free(line);
 
 	/* step 3: invoke tar to build the archive */
-	int error = 0;
-	rc = fork();
-	if (rc == 0) {
-		execlp("tar",
-		       "tar",
-		       "--directory", "/tmp",
-		       "--create",
-		       "--gzip",
-		       "--file", archive_file,
-		       archive_dir,
-		       NULL);
-		fprintf(stderr, "exec: tar:");
-		perror("");
-		exit(EXIT_FAILURE);
-	}
-	else if (rc > 0) {
-		int status;
-		wait(&status);
-		if (!(WIFEXITED(status) && WEXITSTATUS(status) == 0)) {
-			fprintf(stderr, "ftag export: child process exited abnormally\n");
-			error = 1;
-		}
-	}
-	else {
-		perror("fork");
-		error = 1;
-	}
-
-	/* step 4: clean /tmp */
-	execlp("rm", "rm", "--recursive", "--force", tmp_dir, NULL);
-	if (error)
+	char *cmd_tar[] = {
+		"tar",
+		"--directory", "/tmp",
+		"--create",
+		"--gzip",
+		"--file", archive_file,
+		archive_dir,
+		NULL
+	};
+	rc = ftag_execvp(cmd_tar, 0);
+	char *cmd_rm[]	= {
+		"rm",
+		"--recursive",
+		"--force",
+		tmp_dir,
+		NULL
+	};
+	ftag_execvp(cmd_rm, 1);
+	if (rc != 0)
 		exit(EXIT_FAILURE);
 }