[PATCH v5 8/8] convert: Update subprocess_read_status to not die on EOF

[Ben Peart]

Enable sub-processes to gracefully handle when the process dies by
updating subprocess_read_status to return an error on EOF instead of
dying.

Update apply_multi_file_filter to take advantage of the revised
subprocess_read_status.

Signed-off-by: Ben Peart <benpe...@microsoft.com>
---
 convert.c     | 10 ++++++++--
 sub-process.c | 10 +++++++---
 sub-process.h |  2 +-
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/convert.c b/convert.c
index baa41da760..9e181e27ad 100644
--- a/convert.c
+++ b/convert.c
@@ -629,7 +629,10 @@ static int apply_multi_file_filter(const char *path, const 
char *src, size_t len
        if (err)
                goto done;
 
-       subprocess_read_status(process->out, &filter_status);
+       err = subprocess_read_status(process->out, &filter_status);
+       if (err)
+               goto done;
+
        err = strcmp(filter_status.buf, "success");
        if (err)
                goto done;
@@ -638,7 +641,10 @@ static int apply_multi_file_filter(const char *path, const 
char *src, size_t len
        if (err)
                goto done;
 
-       subprocess_read_status(process->out, &filter_status);
+       err = subprocess_read_status(process->out, &filter_status);
+       if (err)
+               goto done;
+
        err = strcmp(filter_status.buf, "success");
 
 done:
diff --git a/sub-process.c b/sub-process.c
index 60bb650012..c5057cafcd 100644
--- a/sub-process.c
+++ b/sub-process.c
@@ -30,13 +30,15 @@ struct subprocess_entry *subprocess_find_entry(const char 
*cmd)
        return hashmap_get(&subprocess_map, &key, NULL);
 }
 
-void subprocess_read_status(int fd, struct strbuf *status)
+int subprocess_read_status(int fd, struct strbuf *status)
 {
        struct strbuf **pair;
        char *line;
+       int len;
+
        for (;;) {
-               line = packet_read_line(fd, NULL);
-               if (!line)
+               len = packet_read_line_gently(fd, NULL, &line);
+               if ((len == -1) || !line)
                        break;
                pair = strbuf_split_str(line, '=', 2);
                if (pair[0] && pair[0]->len && pair[1]) {
@@ -48,6 +50,8 @@ void subprocess_read_status(int fd, struct strbuf *status)
                }
                strbuf_list_free(pair);
        }
+
+       return len == -1 ? len : 0;
 }
 
 void subprocess_stop(struct subprocess_entry *entry)
diff --git a/sub-process.h b/sub-process.h
index 0cf1760a0a..5a1eeeece0 100644
--- a/sub-process.h
+++ b/sub-process.h
@@ -41,6 +41,6 @@ static inline struct child_process 
*subprocess_get_child_process(
  * key/value pairs and return the value from the last "status" packet
  */
 
-void subprocess_read_status(int fd, struct strbuf *status);
+int subprocess_read_status(int fd, struct strbuf *status);
 
 #endif
-- 
2.12.0.windows.1.31.g1548525701.dirty