# HG changeset patch
# User Kristian H?gsberg <krh@redhat.com>
# Date 1207542927 14400
# Node ID d290269008563b1c6b57a1413dbdf47df5af353f
# Parent  b38fc517ea046a162e21263daa32af1b01be9ab0
Create the new repo file O_EXCL to prevent racing with another razor process.

And remember to clean it up on exit paths.

diff -r b38fc517ea04 -r d29026900856 main.c
--- a/main.c	Mon Apr 07 00:06:22 2008 -0400
+++ b/main.c	Mon Apr 07 00:35:27 2008 -0400
@@ -5,6 +5,7 @@
 #include <string.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <fcntl.h>
 #include <dirent.h>
 #include <curl/curl.h>
 #include <fnmatch.h>
@@ -530,33 +531,50 @@
 	struct razor_transaction *trans;
 	char path[PATH_MAX], new_path[PATH_MAX];
 	CURL *curl;
-	int errors;
+	int errors, fd;
+
+	/* Create the new next repo file up front to ensure exclusive
+	 * access. */
+	snprintf(new_path, sizeof new_path,
+		 "%s%s/%s", root, razor_root_path, next_repo_filename);
+	fd = open(new_path, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0666);
+	if (fd < 0) {
+		fprintf(stderr, "failed to get lock file, "
+			"maybe previous operation crashed?\n");
+
+		/* FIXME: Use fcntl advisory locking to figure out
+		 * whether previous operation crashed or is still in
+		 * progress. */
+
+		return -1;
+	}
 
 	upstream = razor_set_open(rawhide_repo_filename);
 	snprintf(path, sizeof path,
 		 "%s%s/%s", root, razor_root_path, system_repo_filename);
 	system = razor_set_open(path);
-	if (system == NULL || upstream == NULL)
+	if (system == NULL || upstream == NULL) {
+		unlink(new_path);
 		return 1;
+	}
 	trans = razor_transaction_create(system, upstream,
 					 argc, argv, 0, NULL);
 	errors = razor_transaction_describe(trans);
-	if (errors)
+	if (errors) {
+		unlink(new_path);
 		return 1;
+	}
 
 	next = razor_transaction_finish(trans);
 
-	/* FIXME: Need razor_set_write_to_fd() so we can open it excl
-	 * up front here or fail if it already exists. */
-	snprintf(new_path, sizeof new_path,
-		 "%s%s/%s", root, razor_root_path, next_repo_filename);
-
-	razor_set_write(next, new_path);
+	razor_set_write_to_fd(next, fd);
 	printf("wrote %s\n", new_path);
 
 	curl = curl_easy_init();
-	if (curl == NULL)
+	if (curl == NULL) {
+		unlink(new_path);
 		return 1;
+	}
 	razor_set_diff(system, next, download_package, curl);	
 	curl_easy_cleanup(curl);
 
diff -r b38fc517ea04 -r d29026900856 razor.c
--- a/razor.c	Mon Apr 07 00:06:22 2008 -0400
+++ b/razor.c	Mon Apr 07 00:35:27 2008 -0400
@@ -198,13 +198,13 @@
 }
 
 int
-razor_set_write(struct razor_set *set, const char *filename)
+razor_set_write_to_fd(struct razor_set *set, int fd)
 {
 	char data[4096];
 	struct razor_set_header *header = (struct razor_set_header *) data;
 	struct array *a;
 	uint32_t offset;
-	int i, fd;
+	int i;
 
 	memset(data, 0, sizeof data);
 	header->magic = RAZOR_MAGIC;
@@ -225,10 +225,6 @@
 	header->sections[i].offset = 0;
 	header->sections[i].size = 0;
 
-	fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0666);
-	if (fd < 0)
-		return -1;
-
 	razor_write(fd, data, sizeof data);
 	memset(data, 0, sizeof data);
 	for (i = 0; i < ARRAY_SIZE(razor_sections); i++) {
@@ -239,11 +235,27 @@
 		razor_write(fd, data, ALIGN(a->size, 4096) - a->size);
 	}
 
-	close(fd);
-
 	return 0;
 }
 
+int
+razor_set_write(struct razor_set *set, const char *filename)
+{
+	int fd, status;
+
+	fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0666);
+	if (fd < 0)
+		return -1;
+
+	status = razor_set_write_to_fd(set, fd);
+	if (status) {
+	    close(fd);
+	    return status;
+	}
+
+	return close(fd);
+}
+
 void
 razor_build_evr(char *evr_buf, int size, const char *epoch,
 		const char *version, const char *release)
diff -r b38fc517ea04 -r d29026900856 razor.h
--- a/razor.h	Mon Apr 07 00:06:22 2008 -0400
+++ b/razor.h	Mon Apr 07 00:35:27 2008 -0400
@@ -26,6 +26,7 @@
 struct razor_set *razor_set_create(void);
 struct razor_set *razor_set_open(const char *filename);
 void razor_set_destroy(struct razor_set *set);
+int razor_set_write_to_fd(struct razor_set *set, int fd);
 int razor_set_write(struct razor_set *set, const char *filename);
 
 struct razor_package *