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pinky: promptly diagnose write errors

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In some cases 'pinky' could run forever until interrupted:

    $ ln -s /dev/zero ~/.plan
    $ ln -s /dev/zero ~/.project
    $ timeout -v 5 pinky -l collin > /dev/full
    timeout: sending signal TERM to command ‘pinky’

After this change it will exit upon failing to write to standard output:

    $ timeout -v 5 ./src/pinky -l collin > /dev/full
    pinky: write error: No space left on device

* src/pinky.c: Include fadvise.h, filenamecat.h, full-write.h, and
ioblksize.h.
(cat_file): New function.
(print_entry): Check if standard output has it's error flag set after
printing a user entry.
(print_long_entry): Likewise. Use the new cat_file function.
* NEWS: Mention the improvement.
This commit is contained in:
Collin Funk 2025-12-04 22:14:31 -08:00
parent 796b8d1a66
commit 3c405ae0b6
2 changed files with 42 additions and 44 deletions
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3
NEWS
View File

@ -48,6 +48,9 @@ GNU coreutils NEWS -*- outline -*-
csplit, ls, and sort, now handle a more complete set of terminating signals.
'pinky' will now exit immediately upon receiving a write error, which is
significant when reading large plan or project files.
'timeout' on Linux will always terminate the child in the case where the
timeout process itself dies, like when it receives a KILL signal for example.

83
src/pinky.c
View File

@ -26,7 +26,11 @@
#include "system.h"
#include "canon-host.h"
#include "fadvise.h"
#include "filenamecat.h"
#include "full-write.h"
#include "hard-locale.h"
#include "ioblksize.h"
#include "readutmp.h"
/* The official name of this program (e.g., no 'g' prefix). */
@ -309,6 +313,36 @@ print_entry (STRUCT_UTMP const *utmp_ent)
#endif
putchar ('\n');
if (ferror (stdout))
write_error ();
}
/* If FILE exists in HOME, print it to standard output, preceded by HEADER. */
static void
cat_file (char const *header, char const *home, char const *file)
{
char *full_name = file_name_concat (home, file, nullptr);
int fd = open (full_name, O_RDONLY);
if (0 <= fd)
{
idx_t header_len = strlen (header);
if (write (STDOUT_FILENO, header, header_len) != header_len)
write_error ();
fdadvise (fd, 0, 0, FADVISE_SEQUENTIAL);
char buf[IO_BUFSIZE];
for (ssize_t bytes_read; 0 < (bytes_read = read (fd, buf, sizeof buf));)
if (full_write (STDOUT_FILENO, buf, bytes_read) != bytes_read)
write_error ();
close (fd);
}
free (full_name);
}
/* Display a verbose line of information about UTMP_ENT. */
@ -355,54 +389,15 @@ print_long_entry (const char name[])
}
if (include_project)
{
FILE *stream;
char buf[1024];
char const *const baseproject = "/.project";
char *const project =
xmalloc (strlen (pw->pw_dir) + strlen (baseproject) + 1);
stpcpy (stpcpy (project, pw->pw_dir), baseproject);
stream = fopen (project, "r");
if (stream)
{
size_t bytes;
printf (_("Project: "));
while ((bytes = fread (buf, 1, sizeof (buf), stream)) > 0)
fwrite (buf, 1, bytes, stdout);
fclose (stream);
}
free (project);
}
cat_file (_("Project: "), pw->pw_dir, ".project");
if (include_plan)
{
FILE *stream;
char buf[1024];
char const *const baseplan = "/.plan";
char *const plan =
xmalloc (strlen (pw->pw_dir) + strlen (baseplan) + 1);
stpcpy (stpcpy (plan, pw->pw_dir), baseplan);
stream = fopen (plan, "r");
if (stream)
{
size_t bytes;
printf (_("Plan:\n"));
while ((bytes = fread (buf, 1, sizeof (buf), stream)) > 0)
fwrite (buf, 1, bytes, stdout);
fclose (stream);
}
free (plan);
}
cat_file (_("Plan:\n"), pw->pw_dir, ".plan");
putchar ('\n');
if (ferror (stdout))
write_error ();
}
/* Print the username of each valid entry and the number of valid entries