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authorPaul Eggert <eggert@cs.ucla.edu>2005-03-30 05:18:37 +0000
committerPaul Eggert <eggert@cs.ucla.edu>2005-03-30 05:18:37 +0000
commit196fb1bc5cec0b39eb3049de88561cc63b040aa3 (patch)
treee9830ccb01ff562db5dfdd0e5c9ceb38c491e690 /lib
parenta3710b1ef6942fa877a243d33632960aea05237d (diff)
downloadcoreutils-196fb1bc5cec0b39eb3049de88561cc63b040aa3.tar.xz
(read_utmp): New arg OPTIONS. All uses changed.
Include signal.h, stdbool.h. (desirable_utmp_entry): New function. (read_utmp) [defined UTMP_NAME_FUNCTION]: Redo memory allocation using x2nrealloc, to simplify logic. (read_utmp) [!defined UTMP_NAME_FUNCTION]: Check for overflow in size calculation.
Diffstat (limited to 'lib')
-rw-r--r--lib/readutmp.c59
1 files changed, 42 insertions, 17 deletions
diff --git a/lib/readutmp.c b/lib/readutmp.c
index 0f844e844..c44b47fa7 100644
--- a/lib/readutmp.c
+++ b/lib/readutmp.c
@@ -1,5 +1,5 @@
/* GNU's read utmp module.
- Copyright (C) 1992-2001, 2003, 2004 Free Software Foundation, Inc.
+ Copyright (C) 1992-2001, 2003, 2004, 2005 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -26,6 +26,8 @@
#include <sys/types.h>
#include <sys/stat.h>
+#include <signal.h>
+#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
@@ -35,6 +37,10 @@
# include "unlocked-io.h"
#endif
+#ifndef SIZE_MAX
+# define SIZE_MAX ((size_t) -1)
+#endif
+
/* Copy UT->ut_name into storage obtained from malloc. Then remove any
trailing spaces from the copy, NUL terminate it, and return the copy. */
@@ -56,19 +62,32 @@ extract_trimmed_name (const STRUCT_UTMP *ut)
return trimmed_name;
}
+/* Is the utmp entry U desired by the user who asked for OPTIONS? */
+
+static inline bool
+desirable_utmp_entry (STRUCT_UTMP const *u, int options)
+{
+ return ! (options & READ_UTMP_CHECK_PIDS
+ && (UT_PID (u) <= 0
+ || (kill (UT_PID (u), 0) < 0 && errno == ESRCH)));
+}
+
/* Read the utmp entries corresponding to file FILENAME into freshly-
malloc'd storage, set *UTMP_BUF to that pointer, set *N_ENTRIES to
the number of entries, and return zero. If there is any error,
- return -1, setting errno, and don't modify the parameters. */
+ return -1, setting errno, and don't modify the parameters.
+ If OPTIONS & READ_UTMP_CHECK_PIDS is nonzero, omit entries whose
+ process-IDs do not currently exist. */
#ifdef UTMP_NAME_FUNCTION
int
-read_utmp (const char *filename, size_t *n_entries, STRUCT_UTMP **utmp_buf)
+read_utmp (const char *filename, size_t *n_entries, STRUCT_UTMP **utmp_buf,
+ int options)
{
- size_t n_read;
- size_t n_alloc = 4;
- STRUCT_UTMP *utmp = xmalloc (n_alloc * sizeof *utmp);
+ size_t n_read = 0;
+ size_t n_alloc = 0;
+ STRUCT_UTMP *utmp = NULL;
STRUCT_UTMP *u;
/* Ignore the return value for now.
@@ -79,17 +98,14 @@ read_utmp (const char *filename, size_t *n_entries, STRUCT_UTMP **utmp_buf)
SET_UTMP_ENT ();
- n_read = 0;
while ((u = GET_UTMP_ENT ()) != NULL)
- {
- if (n_read == n_alloc)
- {
- utmp = xnrealloc (utmp, n_alloc, 2 * sizeof *utmp);
- n_alloc *= 2;
- }
- ++n_read;
- utmp[n_read - 1] = *u;
- }
+ if (desirable_utmp_entry (u, options))
+ {
+ if (n_read == n_alloc)
+ utmp = x2nrealloc (utmp, &n_alloc, sizeof *utmp);
+
+ utmp[n_read++] = *u;
+ }
END_UTMP_ENT ();
@@ -108,6 +124,8 @@ read_utmp (const char *filename, size_t *n_entries, STRUCT_UTMP **utmp_buf)
struct stat file_stats;
size_t n_read;
size_t size;
+ size_t i;
+ size_t n_desired;
STRUCT_UTMP *buf;
utmp = fopen (filename, "r");
@@ -121,6 +139,8 @@ read_utmp (const char *filename, size_t *n_entries, STRUCT_UTMP **utmp_buf)
errno = e;
return -1;
}
+ if (! (0 <= file_stats.st_size && file_stats.st_size <= SIZE_MAX))
+ xalloc_die ();
size = file_stats.st_size;
buf = xmalloc (size);
n_read = fread (buf, sizeof *buf, size / sizeof *buf, utmp);
@@ -140,7 +160,12 @@ read_utmp (const char *filename, size_t *n_entries, STRUCT_UTMP **utmp_buf)
return -1;
}
- *n_entries = n_read;
+ n_desired = 0;
+ for (i = 0; i < n_read; i++)
+ if (desirable_utmp_entry (&utmp[i], options))
+ utmp[n_desired++] = utmp[i];
+
+ *n_entries = n_desired;
*utmp_buf = buf;
return 0;