commit cea56af185eae45b1f0963351e3d4daa1cbde521

Author: Florian Weimer <fweimer@redhat.com>

Date:   Thu Apr 2 17:09:36 2020 +0200

    support: Change xgetline to return 0 on EOF

    The advantage is that the buffer will always contain the number

    of characters as returned from the function, which allows one to use

    a sequence like

      /* No more audit module output.  */

      line_length = xgetline (&buffer, &buffer_length, fp);

      TEST_COMPARE_BLOB ("", 0, buffer, line_length);

    to check for an expected EOF, while also reporting any unexpected

    extra data encountered.

    Reviewed-by: Carlos O'Donell <carlos@redhat.com>

diff --git a/support/support_process_state.c b/support/support_process_state.c

index 76dc798728ece0d9..e303c78fc874b2f9 100644

--- a/support/support_process_state.c

+++ b/support/support_process_state.c

@@ -59,7 +59,7 @@ support_process_state_wait (pid_t pid, enum support_process_state state)

   for (;;)

     {

       char cur_state = -1;

-      while (xgetline (&line, &linesiz, fstatus) != -1)

+      while (xgetline (&line, &linesiz, fstatus) > 0)

 	if (strncmp (line, "State:", strlen ("State:")) == 0)

 	  {

 	    TEST_COMPARE (sscanf (line, "%*s %c", &cur_state), 1);

diff --git a/support/xgetline.c b/support/xgetline.c

index 180bc2db95a9c5d4..d91c09ac108b4c75 100644

--- a/support/xgetline.c

+++ b/support/xgetline.c

@@ -18,16 +18,22 @@

 #include <support/xstdio.h>

 #include <support/check.h>

-#include <errno.h>

-ssize_t

+size_t

 xgetline (char **lineptr, size_t *n, FILE *stream)

 {

-  int old_errno = errno;

-  errno = 0;

-  size_t ret = getline (lineptr, n, stream);

-  if (!feof (stream) && ferror (stream))

-    FAIL_EXIT1 ("getline failed: %m");

-  errno = old_errno;

+  TEST_VERIFY (!ferror (stream));

+  ssize_t ret = getline (lineptr, n, stream);

+  if (ferror (stream))

+    {

+      TEST_VERIFY (ret < 0);

+      FAIL_EXIT1 ("getline: %m");

+    }

+  if (feof (stream))

+    {

+      TEST_VERIFY (ret <= 0);

+      return 0;

+    }

+  TEST_VERIFY (ret > 0);

   return ret;

 }

diff --git a/support/xstdio.h b/support/xstdio.h

index 9446b1f27b0f881e..36071cf78822ec8d 100644

--- a/support/xstdio.h

+++ b/support/xstdio.h

@@ -27,7 +27,10 @@ __BEGIN_DECLS

 FILE *xfopen (const char *path, const char *mode);

 void xfclose (FILE *);

-ssize_t xgetline (char **lineptr, size_t *n, FILE *stream);

+/* Read a line from FP, using getline.  *BUFFER must be NULL, or a

+   heap-allocated pointer of *LENGTH bytes.  Return the number of

+   bytes in the line if a line was read, or 0 on EOF.  */

+size_t xgetline (char **lineptr, size_t *n, FILE *stream);

 __END_DECLS