fix edge cases

If a file an exact multiple of the max buffer size were sponged, it
would fail at the end due to trying to write 0 remaining bytes from the
buffer to the temp file. A similar bug occurred if sponge's input was
empty. Amazing how such a seemingly simple thing can get so tricky..

Also added check for read error from the temp file, just in case.

diff --git a/sponge.c b/sponge.c
index 4a56222cbc4e456920609cb8d355ee5c87fde8ea..948edf0cc70ef5295e9b8fb5b27a724f9b9535c7 100644 (file)
--- a/sponge.c
+++ b/sponge.c
@@ -206,11 +206,14 @@ static void copy_tmpfile(FILE *tmpfile, FILE *outfd) {
                fclose(tmpfile);
                exit(1);
        }
-       // XXX I'd catch signals or writes errors here, but I
-       // I don't think it matters as the file is overwritten
-       while(fread(buf, BUFF_SIZE, 1, tmpfile) == 1) {
+       while (fread(buf, BUFF_SIZE, 1, tmpfile) > 0) {
                write_buff_out(buf, BUFF_SIZE, outfd);
        }
+       if (ferror(tmpfile)) {
+               perror("read temporary file");
+               fclose(tmpfile);
+               exit(1);
+       }
        fclose(tmpfile);
        fclose(outfd);
 }
@@ -274,7 +277,8 @@ int main (int argc, char **argv) {
        }
        if (tmpfile) {
                /* write whatever we have in memory to tmpfile */
-               write_buff_tmp(bufstart, bufused, tmpfile);
+               if (bufused) 
+                       write_buff_tmp(bufstart, bufused, tmpfile);
                struct stat statbuf;
                if (outname && !stat(outname, &statbuf)) {
                        /* regular file */
@@ -306,7 +310,8 @@ int main (int argc, char **argv) {
                                exit(1);
                        }
                }
-               write_buff_out(bufstart, bufused, outfd);
+               if (bufused)
+                       write_buff_out(bufstart, bufused, outfd);
                fclose(outfd);
        }