1 files changed, 124 insertions, 0 deletions
diff --git a/write_or_die.c b/write_or_die.c
new file mode 100644
index 0000000000..e4c8e225fd
--- /dev/null
+++ b/write_or_die.c
@@ -0,0 +1,124 @@
+#include "cache.h"
+
+/*
+ * Some cases use stdio, but want to flush after the write
+ * to get error handling (and to get better interactive
+ * behaviour - not buffering excessively).
+ *
+ * Of course, if the flush happened within the write itself,
+ * we've already lost the error code, and cannot report it any
+ * more. So we just ignore that case instead (and hope we get
+ * the right error code on the flush).
+ *
+ * If the file handle is stdout, and stdout is a file, then skip the
+ * flush entirely since it's not needed.
+ */
+void maybe_flush_or_die(FILE *f, const char *desc)
+{
+	static int skip_stdout_flush = -1;
+	struct stat st;
+	char *cp;
+
+	if (f == stdout) {
+		if (skip_stdout_flush < 0) {
+			cp = getenv("GIT_FLUSH");
+			if (cp)
+				skip_stdout_flush = (atoi(cp) == 0);
+			else if ((fstat(fileno(stdout), &st) == 0) &&
+				 S_ISREG(st.st_mode))
+				skip_stdout_flush = 1;
+			else
+				skip_stdout_flush = 0;
+		}
+		if (skip_stdout_flush && !ferror(f))
+			return;
+	}
+	if (fflush(f)) {
+		/*
+		 * On Windows, EPIPE is returned only by the first write()
+		 * after the reading end has closed its handle; subsequent
+		 * write()s return EINVAL.
+		 */
+		if (errno == EPIPE || errno == EINVAL)
+			exit(0);
+		die("write failure on %s: %s", desc, strerror(errno));
+	}
+}
+
+ssize_t read_in_full(int fd, void *buf, size_t count)
+{
+	char *p = buf;
+	ssize_t total = 0;
+
+	while (count > 0) {
+		ssize_t loaded = xread(fd, p, count);
+		if (loaded <= 0)
+			return total ? total : loaded;
+		count -= loaded;
+		p += loaded;
+		total += loaded;
+	}
+
+	return total;
+}
+
+ssize_t write_in_full(int fd, const void *buf, size_t count)
+{
+	const char *p = buf;
+	ssize_t total = 0;
+
+	while (count > 0) {
+		ssize_t written = xwrite(fd, p, count);
+		if (written < 0)
+			return -1;
+		if (!written) {
+			errno = ENOSPC;
+			return -1;
+		}
+		count -= written;
+		p += written;
+		total += written;
+	}
+
+	return total;
+}
+
+void fsync_or_die(int fd, const char *msg)
+{
+	if (fsync(fd) < 0) {
+		die("%s: fsync error (%s)", msg, strerror(errno));
+	}
+}
+
+void write_or_die(int fd, const void *buf, size_t count)
+{
+	if (write_in_full(fd, buf, count) < 0) {
+		if (errno == EPIPE)
+			exit(0);
+		die("write error (%s)", strerror(errno));
+	}
+}
+
+int write_or_whine_pipe(int fd, const void *buf, size_t count, const char *msg)
+{
+	if (write_in_full(fd, buf, count) < 0) {
+		if (errno == EPIPE)
+			exit(0);
+		fprintf(stderr, "%s: write error (%s)\n",
+			msg, strerror(errno));
+		return 0;
+	}
+
+	return 1;
+}
+
+int write_or_whine(int fd, const void *buf, size_t count, const char *msg)
+{
+	if (write_in_full(fd, buf, count) < 0) {
+		fprintf(stderr, "%s: write error (%s)\n",
+			msg, strerror(errno));
+		return 0;
+	}
+
+	return 1;
+}