Move modules to ccan/ tools to tools/

[ccan] / ccan / noerr / _info.c

diff --git a/ccan/noerr/_info.c b/ccan/noerr/_info.c
new file mode 100644 (file)
index 0000000..96fbbcd
--- /dev/null
+++ b/ccan/noerr/_info.c
@@ -0,0 +1,54 @@
+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * noerr - routines for cleaning up without blatting errno
+ *
+ * It is a good idea to follow the standard C convention of setting errno in
+ * your own helper functions.  Unfortunately, care must be taken in the error
+ * paths as most standard functions can (and do) overwrite errno, even if they
+ * succeed.
+ *
+ * Example:
+ *     #include <sys/types.h>
+ *     #include <sys/stat.h>
+ *     #include <fcntl.h>
+ *
+ *     bool write_string_to_file(const char *file, const char *string)
+ *     {
+ *             int ret, fd = open(file, O_WRONLY|O_CREAT|O_EXCL, 0600);
+ *             if (fd < 0)
+ *                     return false;
+ *             ret = write(fd, string, strlen(string));
+ *             if (ret < 0) {
+ *                     // Preserve errno from write above.
+ *                     close_noerr(fd);
+ *                     unlink_noerr(file);
+ *                     return false;
+ *             }
+ *             if (close(fd) != 0) {
+ *                     // Again, preserve errno.
+ *                     unlink_noerr(file);
+ *                     return false;
+ *             }
+ *             // A short write means out of space.
+ *             if (ret < strlen(string)) {
+ *                     unlink(file);
+ *                     errno = ENOSPC;
+ *                     return false;
+ *             }
+ *             return true;
+ *     }
+ */
+int main(int argc, char *argv[])
+{
+       if (argc != 2)
+               return 1;
+
+       if (strcmp(argv[1], "depends") == 0)
+               /* Nothing. */
+               return 0;
+
+       return 1;
+}