merge-recursive: don't segfault while handling rename clashes

diff --git a/rerere.c b/rerere.c
index 02931a151f1abe183763c9a1edb65ffd36d83bc3..718fb526dd1fbbc5de18784586d37d6069807b77 100644 (file)
--- a/rerere.c
+++ b/rerere.c
@@ -70,6 +70,19 @@ static int write_rr(struct string_list *rr, int out_fd)
        return 0;
 }
 
+static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
+{
+       if (!count || *err)
+               return;
+       if (fwrite(p, count, 1, fp) != 1)
+               *err = errno;
+}
+
+static inline void ferr_puts(const char *s, FILE *fp, int *err)
+{
+       ferr_write(s, strlen(s), fp, err);
+}
+
 static int handle_file(const char *path,
         unsigned char *sha1, const char *output)
 {
@@ -82,6 +95,7 @@ static int handle_file(const char *path,
        struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
        FILE *f = fopen(path, "r");
        FILE *out = NULL;
+       int wrerror = 0;
 
        if (!f)
                return error("Could not open %s", path);
@@ -118,11 +132,11 @@ static int handle_file(const char *path,
                        hunk_no++;
                        hunk = RR_CONTEXT;
                        if (out) {
-                               fputs("<<<<<<<\n", out);
-                               fwrite(one.buf, one.len, 1, out);
-                               fputs("=======\n", out);
-                               fwrite(two.buf, two.len, 1, out);
-                               fputs(">>>>>>>\n", out);
+                               ferr_puts("<<<<<<<\n", out, &wrerror);
+                               ferr_write(one.buf, one.len, out, &wrerror);
+                               ferr_puts("=======\n", out, &wrerror);
+                               ferr_write(two.buf, two.len, out, &wrerror);
+                               ferr_puts(">>>>>>>\n", out, &wrerror);
                        }
                        if (sha1) {
                                git_SHA1_Update(&ctx, one.buf ? one.buf : "",
@@ -139,7 +153,7 @@ static int handle_file(const char *path,
                else if (hunk == RR_SIDE_2)
                        strbuf_addstr(&two, buf);
                else if (out)
-                       fputs(buf, out);
+                       ferr_puts(buf, out, &wrerror);
                continue;
        bad:
                hunk = 99; /* force error exit */
@@ -149,8 +163,12 @@ static int handle_file(const char *path,
        strbuf_release(&two);
 
        fclose(f);
-       if (out)
-               fclose(out);
+       if (wrerror)
+               error("There were errors while writing %s (%s)",
+                     path, strerror(wrerror));
+       if (out && fclose(out))
+               wrerror = error("Failed to flush %s: %s",
+                               path, strerror(errno));
        if (sha1)
                git_SHA1_Final(sha1, &ctx);
        if (hunk != RR_CONTEXT) {
@@ -158,6 +176,8 @@ static int handle_file(const char *path,
                        unlink(output);
                return error("Could not parse conflict hunks in %s", path);
        }
+       if (wrerror)
+               return -1;
        return hunk_no;
 }
 
@@ -200,9 +220,13 @@ static int merge(const char *name, const char *path)
        if (!ret) {
                FILE *f = fopen(path, "w");
                if (!f)
-                       return error("Could not write to %s", path);
-               fwrite(result.ptr, result.size, 1, f);
-               fclose(f);
+                       return error("Could not open %s: %s", path,
+                                    strerror(errno));
+               if (fwrite(result.ptr, result.size, 1, f) != 1)
+                       error("Could not write %s: %s", path, strerror(errno));
+               if (fclose(f))
+                       return error("Writing %s failed: %s", path,
+                                    strerror(errno));
        }
 
        free(cur.ptr);