compat: Add simplified merge sort implementation from glibc

diff --git a/write_or_die.c b/write_or_die.c
index a119e1d208445093dd1d2869729eca9435aa020e..e125e11d3b63e3dab9077d7b414e83e7ff7d16ad 100644 (file)
--- a/write_or_die.c
+++ b/write_or_die.c
@@ -1,19 +1,54 @@
 #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)) {
+               if (errno == EPIPE)
+                       exit(0);
+               die("write failure on %s: %s", desc, strerror(errno));
+       }
+}
+
 int read_in_full(int fd, void *buf, size_t count)
 {
        char *p = buf;
        ssize_t total = 0;
-       ssize_t loaded = 0;
 
        while (count > 0) {
-               loaded = xread(fd, p, count);
-               if (loaded <= 0) {
-                       if (total)
-                               return total;
-                       else
-                               return loaded;
-               }
+               ssize_t loaded = xread(fd, p, count);
+               if (loaded <= 0)
+                       return total ? total : loaded;
                count -= loaded;
                p += loaded;
                total += loaded;
@@ -22,30 +57,18 @@ int read_in_full(int fd, void *buf, size_t count)
        return total;
 }
 
-void read_or_die(int fd, void *buf, size_t count)
-{
-       ssize_t loaded;
-
-       loaded = read_in_full(fd, buf, count);
-       if (loaded == 0)
-               die("unexpected end of file");
-       else if (loaded < 0)
-               die("read error (%s)", strerror(errno));
-}
-
 int write_in_full(int fd, const void *buf, size_t count)
 {
        const char *p = buf;
        ssize_t total = 0;
-       ssize_t written = 0;
 
        while (count > 0) {
-               written = xwrite(fd, p, count);
-               if (written <= 0) {
-                       if (total)
-                               return total;
-                       else
-                               return written;
+               ssize_t written = xwrite(fd, p, count);
+               if (written < 0)
+                       return -1;
+               if (!written) {
+                       errno = ENOSPC;
+                       return -1;
                }
                count -= written;
                p += written;
@@ -57,12 +80,7 @@ int write_in_full(int fd, const void *buf, size_t count)
 
 void write_or_die(int fd, const void *buf, size_t count)
 {
-       ssize_t written;
-
-       written = write_in_full(fd, buf, count);
-       if (written == 0)
-               die("disk full?");
-       else if (written < 0) {
+       if (write_in_full(fd, buf, count) < 0) {
                if (errno == EPIPE)
                        exit(0);
                die("write error (%s)", strerror(errno));
@@ -71,14 +89,7 @@ void write_or_die(int fd, const void *buf, size_t count)
 
 int write_or_whine_pipe(int fd, const void *buf, size_t count, const char *msg)
 {
-       ssize_t written;
-
-       written = write_in_full(fd, buf, count);
-       if (written == 0) {
-               fprintf(stderr, "%s: disk full?\n", msg);
-               return 0;
-       }
-       else if (written < 0) {
+       if (write_in_full(fd, buf, count) < 0) {
                if (errno == EPIPE)
                        exit(0);
                fprintf(stderr, "%s: write error (%s)\n",
@@ -91,14 +102,7 @@ int write_or_whine_pipe(int fd, const void *buf, size_t count, const char *msg)
 
 int write_or_whine(int fd, const void *buf, size_t count, const char *msg)
 {
-       ssize_t written;
-
-       written = write_in_full(fd, buf, count);
-       if (written == 0) {
-               fprintf(stderr, "%s: disk full?\n", msg);
-               return 0;
-       }
-       else if (written < 0) {
+       if (write_in_full(fd, buf, count) < 0) {
                fprintf(stderr, "%s: write error (%s)\n",
                        msg, strerror(errno));
                return 0;