* Hook output functions (like printf(3)) with LD_PRELOAD to color stderr (or
* other file descriptors).
*
- * Copyright (C) 2013 Simon Ruderich
+ * Copyright (C) 2013-2018 Simon Ruderich
*
* 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
# define NDEBUG
#endif
+#ifndef TLS
+# define TLS
+#endif
+
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
/* Was ENV_NAME_FDS found and used when init_from_environment() was called?
* This is not true if the process set it manually after initialization. */
static int used_fds_set_by_user;
+/* Was any of our handle_*_pre()/handle_*_post() functions called recursively?
+ * If so don't print the pre/post string for the recursive calls. This is
+ * necessary on some systems (e.g. FreeBSD 9.1) which call multiple hooked
+ * functions while printing a string (e.g. a FILE * and a fd hook function is
+ * called). This is not thread-safe if TLS is not available. */
+static TLS int handle_recursive;
#include "constants.h"
static void handle_file_post(FILE *stream) noinline;
static void handle_fd_pre(int fd) {
+ if (handle_recursive++ > 0) {
+ return;
+ }
+
int saved_errno = errno;
- if (unlikely(!pre_string || !post_string)) {
+ if (unlikely(!pre_string)) {
init_pre_post_string();
}
errno = saved_errno;
}
static void handle_fd_post(int fd) {
+ if (--handle_recursive > 0) {
+ return;
+ }
+
int saved_errno = errno;
/* write() already loaded above in handle_fd_pre(). */
}
static void handle_file_pre(FILE *stream) {
+ if (handle_recursive++ > 0) {
+ return;
+ }
+
int saved_errno = errno;
- if (unlikely(!pre_string || !post_string)) {
+ if (unlikely(!pre_string)) {
init_pre_post_string();
}
errno = saved_errno;
}
static void handle_file_post(FILE *stream) {
+ if (--handle_recursive > 0) {
+ return;
+ }
+
int saved_errno = errno;
/* fwrite() already loaded above in handle_file_pre(). */
int, c, FILE *, stream)
HOOK_FILE2(int, putc, stream,
int, c, FILE *, stream)
+/* The glibc uses a macro for putc() which expands to _IO_putc(). However
+ * sometimes the raw putc() is used as well, not sure why. Make sure to hook
+ * it too. */
+#ifdef putc
+# undef putc
+HOOK_FILE2(int, putc, stream,
+ int, c, FILE *, stream)
+#endif
HOOK_FILE1(int, putchar, stdout,
int, c)
HOOK_FILE1(int, puts, stdout,
/* Same for FreeBSD's libc. However it's more aggressive: The inline writing
* and __swbuf() are also used for normal output (e.g. putc()). Writing to
* stderr is still fine; it always calls __swbuf() as stderr is always
- * unbufferd. */
+ * unbuffered. */
#ifdef HAVE___SWBUF
HOOK_FILE2(int, __swbuf, f, int, c, FILE *, f)
#endif
if (error_one_per_line
&& filename != NULL && linenum != 0
&& filename == last_filename && linenum == last_linenum) {
- return;
+ goto out;
}
last_filename = filename;
last_linenum = linenum;
fprintf(stderr, "\n");
+out:
if (status != 0) {
exit(status);
}
* isn't allowed to perform any memory-modifications before the exec()
* (except the pid_t result variable of vfork()).
*
- * As some programs don't adhere to the standard (e.g. the "child" closes
- * or dups a descriptor before the exec()) and this breaks our tracking of
- * file descriptors (e.g. it gets closed in the parent as well), we just
- * fork() instead. This is in compliance with the POSIX standard and as
- * most systems use copy-on-write anyway not a performance issue. */
+ * As we have to store changes to the file descriptors in memory (e.g. the
+ * "child" closes or dups a descriptor before the exec()) and this
+ * modifies the parent as well due to the semantics of vfork() - thus
+ * breaking the requirements of vfork(), we just use fork instead(). This
+ * is in compliance with the POSIX standard and as most systems use
+ * copy-on-write anyway not a performance issue. */
return fork();
}
#endif
HOOK_FUNC_DEF3(int, execve, char const *, filename, char * const *, argv, char * const *, env) {
DLSYM_FUNCTION(real_execve, "execve");
+ char * const fake_env[] = {NULL};
+ if (env == NULL) {
+ env = fake_env;
+ }
+
/* Count environment variables. */
size_t count = 0;
char * const *x = env;
#ifdef HAVE_EXECVPE
extern char **environ;
int execvpe(char const *file, char * const argv[], char * const envp[]) {
+ int result;
+ char **old_environ = environ;
+
/* Fake the environment so we can reuse execvp(). */
environ = (char **)envp;
/* execvp() updates the environment. */
- return execvp(file, argv);
+ result = execvp(file, argv);
+
+ environ = old_environ;
+ return result;
}
#endif