[ccan] [PATCH v2 06/13] configurator: Print test source without cat

[Kevin Locke]

Windows does not provide cat.  Instead, copy the test source to stdout
using the file stream to which it was written.

Changes since v1:
- Create fwrite_noeintr to avoid EINTR in fwrite without writing any
  data.
- Handle short reads from fread.  This can happen with non-conformant
  libc or if EINTR occurs after reading some data.
- Handle short writes from fwrite.  This can happen with non-conformant
  libc or if EINTR occurs after writing some data.

Signed-off-by: Kevin Locke <ke...@kevinlocke.name>
---
 tools/configurator/configurator.c | 48 +++++++++++++++++++++++++++++++++++----
 1 file changed, 43 insertions(+), 5 deletions(-)

diff --git a/tools/configurator/configurator.c 
b/tools/configurator/configurator.c
index 31e3d11..51d7ac8 100644
--- a/tools/configurator/configurator.c
+++ b/tools/configurator/configurator.c
@@ -438,6 +438,42 @@ static size_t fread_noeintr(void *ptr, size_t size, size_t 
nitems,
        return ret;
 }
 
+static size_t fwrite_noeintr(const void *ptr, size_t size, size_t nitems,
+               FILE *stream)
+{
+       size_t ret;
+
+       do {
+               errno = 0;
+               ret = fwrite(ptr, size, nitems, stream);
+       } while (ret == 0 && errno == EINTR);
+
+       return ret;
+}
+
+static size_t fcopy(FILE *fsrc, FILE *fdst)
+{
+       char buffer[BUFSIZ];
+       size_t copied = 0, rsize;
+
+       while ((rsize = fread_noeintr(buffer, 1, BUFSIZ, fsrc)) > 0) {
+               size_t wsize, wtotal = 0;
+
+               while (wtotal < rsize &&
+                      ((wsize = fwrite_noeintr(buffer + wtotal, 1,
+                                               rsize - wtotal, fdst)) > 0)) {
+                       wtotal += wsize;
+               }
+
+               if (wtotal < rsize)
+                       break;
+
+               copied += wtotal;
+       }
+
+       return copied;
+}
+
 static char *grab_stream(FILE *file)
 {
        size_t max, ret, size = 0;
@@ -562,7 +598,7 @@ static bool run_test(const char *cmd, struct test *test)
                }
        }
 
-       outf = fopen(INPUT_FILE, "w");
+       outf = fopen(INPUT_FILE, verbose > 1 ? "w+" : "w");
        if (!outf)
                err(1, "creating %s", INPUT_FILE);
 
@@ -593,11 +629,13 @@ static bool run_test(const char *cmd, struct test *test)
                abort();
 
        }
-       fclose(outf);
 
-       if (verbose > 1)
-               if (system("cat " INPUT_FILE) == -1)
-                       ;
+       if (verbose > 1) {
+               fseek(outf, 0, SEEK_SET);
+               fcopy(outf, stdout);
+       }
+
+       fclose(outf);
 
        newcmd = strdup(cmd);
 
-- 
2.9.3

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