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wget/src/log.c

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/* Messages logging.
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Copyright (C) 1998, 2000, 2001 Free Software Foundation, Inc.
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This file is part of GNU Wget.
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GNU Wget is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
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GNU Wget is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
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along with Wget; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
In addition, as a special exception, the Free Software Foundation
gives permission to link the code of its release of Wget with the
OpenSSL project's "OpenSSL" library (or with modified versions of it
that use the same license as the "OpenSSL" library), and distribute
the linked executables. You must obey the GNU General Public License
in all respects for all of the code used other than "OpenSSL". If you
modify this file, you may extend this exception to your version of the
file, but you are not obligated to do so. If you do not wish to do
so, delete this exception statement from your version. */
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#include <config.h>
#include <stdio.h>
#ifdef HAVE_STRING_H
# include <string.h>
#else
# include <strings.h>
#endif
#include <stdlib.h>
#ifdef WGET_USE_STDARG
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# include <stdarg.h>
#else
# include <varargs.h>
#endif
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <assert.h>
#include <errno.h>
#include "wget.h"
#include "utils.h"
#include "log.h"
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#ifndef errno
extern int errno;
#endif
/* This file impplement support for "logging". Logging means printing
output, plus several additional features:
- Cataloguing output by importance. You can specify that a log
message is "verbose" or "debug", and it will not be printed unless
in verbose or debug mode, respectively.
- Redirecting the log to the file. When Wget's output goes to the
terminal, and Wget receives SIGHUP, all further output is
redirected to a log file. When this is the case, Wget can also
print the last several lines of "context" to the log file so that
it does not begin in the middle of a line. For this to work, the
logging code stores the last several lines of context. Callers may
request for certain output not to be stored.
- Inhibiting output. When Wget receives SIGHUP, but redirecting
the output fails, logging is inhibited. */
/* The file descriptor used for logging. This is NULL before log_init
is called; logging functions log to stderr then. log_init sets it
either to stderr or to a file pointer obtained from fopen(). If
logging is inhibited, logfp is set back to NULL. */
static FILE *logfp;
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/* If non-zero, it means logging is inhibited, i.e. nothing is printed
or stored. */
static int inhibit_logging;
/* Whether the last output lines are stored for use as context. */
static int save_context_p;
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/* Whether the log is flushed after each command. */
static int flush_log_p = 1;
/* Whether any output has been received while flush_log_p was 0. */
static int needs_flushing;
/* In the event of a hang-up, and if its output was on a TTY, Wget
redirects its output to `wget-log'.
For the convenience of reading this newly-created log, we store the
last several lines ("screenful", hence the choice of 24) of Wget
output, and dump them as context when the time comes. */
#define SAVED_LOG_LINES 24
/* log_lines is a circular buffer that stores SAVED_LOG_LINES lines of
output. log_line_current always points to the position in the
buffer that will be written to next. When log_line_current reaches
SAVED_LOG_LINES, it is reset to zero.
The problem here is that we'd have to either (re)allocate and free
strings all the time, or limit the lines to an arbitrary number of
characters. Instead of settling for either of these, we do both:
if the line is smaller than a certain "usual" line length (128
chars by default), a preallocated memory is used. The rare lines
that are longer than 128 characters are malloc'ed and freed
separately. This gives good performance with minimum memory
consumption and fragmentation. */
#define STATIC_LENGTH 128
static struct log_ln {
char static_line[STATIC_LENGTH + 1]; /* statically allocated
line. */
char *malloced_line; /* malloc'ed line, for lines of output
larger than 80 characters. */
char *content; /* this points either to malloced_line
or to the appropriate static_line.
If this is NULL, it means the line
has not yet been used. */
} log_lines[SAVED_LOG_LINES];
/* The current position in the ring. */
static int log_line_current = -1;
/* Whether the most recently written line was "trailing", i.e. did not
finish with \n. This is an important piece of information because
the code is always careful to append data to trailing lines, rather
than create new ones. */
static int trailing_line;
static void check_redirect_output PARAMS ((void));
#define ROT_ADVANCE(num) do { \
if (++num >= SAVED_LOG_LINES) \
num = 0; \
} while (0)
/* Free the log line index with NUM. This calls free on
ln->malloced_line if it's non-NULL, and it also resets
ln->malloced_line and ln->content to NULL. */
static void
free_log_line (int num)
{
struct log_ln *ln = log_lines + num;
if (ln->malloced_line)
{
xfree (ln->malloced_line);
ln->malloced_line = NULL;
}
ln->content = NULL;
}
/* Append bytes in the range [start, end) to one line in the log. The
region is not supposed to contain newlines, except for the last
character (at end[-1]). */
static void
saved_append_1 (const char *start, const char *end)
{
int len = end - start;
if (!len)
return;
/* First, check whether we need to append to an existing line or to
create a new one. */
if (!trailing_line)
{
/* Create a new line. */
struct log_ln *ln;
if (log_line_current == -1)
log_line_current = 0;
else
free_log_line (log_line_current);
ln = log_lines + log_line_current;
if (len > STATIC_LENGTH)
{
ln->malloced_line = strdupdelim (start, end);
ln->content = ln->malloced_line;
}
else
{
memcpy (ln->static_line, start, len);
ln->static_line[len] = '\0';
ln->content = ln->static_line;
}
}
else
{
/* Append to the last line. If the line is malloc'ed, we just
call realloc and append the new string. If the line is
static, we have to check whether appending the new string
would make it exceed STATIC_LENGTH characters, and if so,
convert it to malloc(). */
struct log_ln *ln = log_lines + log_line_current;
if (ln->malloced_line)
{
/* Resize malloc'ed line and append. */
int old_len = strlen (ln->malloced_line);
ln->malloced_line = xrealloc (ln->malloced_line, old_len + len + 1);
memcpy (ln->malloced_line + old_len, start, len);
ln->malloced_line[old_len + len] = '\0';
/* might have changed due to realloc */
ln->content = ln->malloced_line;
}
else
{
int old_len = strlen (ln->static_line);
if (old_len + len > STATIC_LENGTH)
{
/* Allocate memory and concatenate the old and the new
contents. */
ln->malloced_line = (char *)xmalloc (old_len + len + 1);
memcpy (ln->malloced_line, ln->static_line,
old_len);
memcpy (ln->malloced_line + old_len, start, len);
ln->malloced_line[old_len + len] = '\0';
ln->content = ln->malloced_line;
}
else
{
/* Just append to the old, statically allocated
contents. */
memcpy (ln->static_line + old_len, start, len);
ln->static_line[old_len + len] = '\0';
ln->content = ln->static_line;
}
}
}
trailing_line = !(end[-1] == '\n');
if (!trailing_line)
ROT_ADVANCE (log_line_current);
}
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/* Log the contents of S, as explained above. If S consists of
multiple lines, they are logged separately. If S does not end with
a newline, it will form a "trailing" line, to which things will get
appended the next time this function is called. */
static void
saved_append (const char *s)
{
while (*s)
{
const char *end = strchr (s, '\n');
if (!end)
end = s + strlen (s);
else
++end;
saved_append_1 (s, end);
s = end;
}
}
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/* Check X against opt.verbose and opt.quiet. The semantics is as
follows:
* LOG_ALWAYS - print the message unconditionally;
* LOG_NOTQUIET - print the message if opt.quiet is non-zero;
* LOG_NONVERBOSE - print the message if opt.verbose is zero;
* LOG_VERBOSE - print the message if opt.verbose is non-zero. */
#define CHECK_VERBOSE(x) \
switch (x) \
{ \
case LOG_ALWAYS: \
break; \
case LOG_NOTQUIET: \
if (opt.quiet) \
return; \
break; \
case LOG_NONVERBOSE: \
if (opt.verbose || opt.quiet) \
return; \
break; \
case LOG_VERBOSE: \
if (!opt.verbose) \
return; \
}
/* Returns the file descriptor for logging. This is LOGFP, except if
called before log_init, in which case it returns stderr. This is
useful in case someone calls a logging function before log_init.
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If logging is inhibited, return NULL. */
static FILE *
get_log_fp (void)
{
if (inhibit_logging)
return NULL;
if (logfp)
return logfp;
return stderr;
}
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/* Log a literal string S. The string is logged as-is, without a
newline appended. */
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void
logputs (enum log_options o, const char *s)
{
FILE *fp;
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check_redirect_output ();
if (!(fp = get_log_fp ()))
return;
CHECK_VERBOSE (o);
fputs (s, fp);
if (save_context_p)
saved_append (s);
if (flush_log_p)
logflush ();
else
needs_flushing = 1;
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}
struct logvprintf_state {
char *bigmsg;
int expected_size;
int allocated;
};
/* Print a message to the log. A copy of message will be saved to
saved_log, for later reusal by log_dump_context().
Normally we'd want this function to loop around vsnprintf until
sufficient room is allocated, as the Linux man page recommends.
However each call to vsnprintf() must be preceded by va_start and
followed by va_end. Since calling va_start/va_end is possible only
in the function that contains the `...' declaration, we cannot call
vsnprintf more than once. Therefore this function saves its state
to logvprintf_state and signals the parent to call it again.
(An alternative approach would be to use va_copy, but that's not
portable.) */
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static int
log_vprintf_internal (struct logvprintf_state *state, const char *fmt,
va_list args)
{
char smallmsg[128];
char *write_ptr = smallmsg;
int available_size = sizeof (smallmsg);
int numwritten;
FILE *fp = get_log_fp ();
if (!save_context_p)
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{
/* In the simple case just call vfprintf(), to avoid needless
allocation and games with vsnprintf(). */
vfprintf (fp, fmt, args);
goto flush;
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}
if (state->allocated != 0)
{
write_ptr = state->bigmsg;
available_size = state->allocated;
}
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/* The GNU coding standards advise not to rely on the return value
of sprintf(). However, vsnprintf() is a relatively new function
missing from legacy systems. Therefore I consider it safe to
assume that its return value is meaningful. On the systems where
vsnprintf() is not available, we use the implementation from
snprintf.c which does return the correct value. */
numwritten = vsnprintf (write_ptr, available_size, fmt, args);
/* vsnprintf() will not step over the limit given by available_size.
If it fails, it will return either -1 (POSIX?) or the number of
characters that *would have* been written, if there had been
enough room (C99). In the former case, we double the
available_size and malloc to get a larger buffer, and try again.
In the latter case, we use the returned information to build a
buffer of the correct size. */
if (numwritten == -1)
{
/* Writing failed, and we don't know the needed size. Try
again with doubled size. */
int newsize = available_size << 1;
state->bigmsg = xrealloc (state->bigmsg, newsize);
state->allocated = newsize;
return 0;
}
else if (numwritten >= available_size)
{
/* Writing failed, but we know exactly how much space we
need. */
int newsize = numwritten + 1;
state->bigmsg = xrealloc (state->bigmsg, newsize);
state->allocated = newsize;
return 0;
}
/* Writing succeeded. */
saved_append (write_ptr);
fputs (write_ptr, fp);
if (state->bigmsg)
xfree (state->bigmsg);
flush:
if (flush_log_p)
logflush ();
else
needs_flushing = 1;
return 1;
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}
/* Flush LOGFP. Useful while flushing is disabled. */
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void
logflush (void)
{
FILE *fp = get_log_fp ();
if (fp)
fflush (fp);
needs_flushing = 0;
}
/* Enable or disable log flushing. */
void
log_set_flush (int flush)
{
if (flush == flush_log_p)
return;
if (flush == 0)
{
/* Disable flushing by setting flush_log_p to 0. */
flush_log_p = 0;
}
else
{
/* Reenable flushing. If anything was printed in no-flush mode,
flush the log now. */
if (needs_flushing)
logflush ();
flush_log_p = 1;
}
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}
/* (Temporarily) disable storing log to memory. Returns the old
status of storing, with which this function can be called again to
reestablish storing. */
int
log_set_save_context (int savep)
{
int old = save_context_p;
save_context_p = savep;
return old;
}
/* Handle difference in va_start between pre-ANSI and ANSI C. Note
that we always use `...' in function definitions and let ansi2knr
convert it for us. */
#ifdef WGET_USE_STDARG
# define VA_START(args, arg1) va_start (args, arg1)
#else
# define VA_START(args, ignored) va_start (args)
#endif
/* Print a message to the screen or to the log. The first argument
defines the verbosity of the message, and the rest are as in
printf(3). */
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void
logprintf (enum log_options o, const char *fmt, ...)
{
va_list args;
struct logvprintf_state lpstate;
int done;
check_redirect_output ();
if (inhibit_logging)
return;
CHECK_VERBOSE (o);
xzero (lpstate);
do
{
VA_START (args, fmt);
done = log_vprintf_internal (&lpstate, fmt, args);
va_end (args);
}
while (!done);
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}
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#ifdef ENABLE_DEBUG
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/* The same as logprintf(), but does anything only if opt.debug is
non-zero. */
void
debug_logprintf (const char *fmt, ...)
{
if (opt.debug)
{
va_list args;
struct logvprintf_state lpstate;
int done;
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check_redirect_output ();
if (inhibit_logging)
return;
xzero (lpstate);
do
{
VA_START (args, fmt);
done = log_vprintf_internal (&lpstate, fmt, args);
va_end (args);
}
while (!done);
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}
}
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#endif /* ENABLE_DEBUG */
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/* Open FILE and set up a logging stream. If FILE cannot be opened,
exit with status of 1. */
void
log_init (const char *file, int appendp)
{
if (file)
{
logfp = fopen (file, appendp ? "a" : "w");
if (!logfp)
{
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fprintf (stderr, "%s: %s: %s\n", exec_name, file, strerror (errno));
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exit (1);
}
}
else
{
/* The log goes to stderr to avoid collisions with the output if
the user specifies `-O -'. #### Francois Pinard suggests
that it's a better idea to print to stdout by default, and to
stderr only if the user actually specifies `-O -'. He says
this inconsistency is harder to document, but is overall
easier on the user. */
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logfp = stderr;
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if (1
#ifdef HAVE_ISATTY
&& isatty (fileno (logfp))
#endif
)
{
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/* If the output is a TTY, enable save context, i.e. store
the most recent several messages ("context") and dump
them to a log file in case SIGHUP or SIGUSR1 is received
(or Ctrl+Break is pressed under Windows). */
save_context_p = 1;
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}
}
}
/* Close LOGFP, inhibit further logging and free the memory associated
with it. */
void
log_close (void)
{
int i;
if (logfp)
fclose (logfp);
logfp = NULL;
inhibit_logging = 1;
save_context_p = 0;
for (i = 0; i < SAVED_LOG_LINES; i++)
free_log_line (i);
log_line_current = -1;
trailing_line = 0;
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}
/* Dump saved lines to logfp. */
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static void
log_dump_context (void)
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{
int num = log_line_current;
FILE *fp = get_log_fp ();
if (!fp)
return;
if (num == -1)
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return;
if (trailing_line)
ROT_ADVANCE (num);
do
{
struct log_ln *ln = log_lines + num;
if (ln->content)
fputs (ln->content, fp);
ROT_ADVANCE (num);
}
while (num != log_line_current);
if (trailing_line)
if (log_lines[log_line_current].content)
fputs (log_lines[log_line_current].content, fp);
fflush (fp);
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}
/* When SIGHUP or SIGUSR1 are received, the output is redirected
elsewhere. Such redirection is only allowed once. */
enum { RR_NONE, RR_REQUESTED, RR_DONE } redirect_request = RR_NONE;
static const char *redirect_request_signal_name;
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/* Redirect output to `wget-log'. */
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static void
redirect_output (void)
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{
char *logfile;
logfp = unique_create (DEFAULT_LOGFILE, 0, &logfile);
if (logfp)
{
fprintf (stderr, _("\n%s received, redirecting output to `%s'.\n"),
redirect_request_signal_name, logfile);
xfree (logfile);
/* Dump the context output to the newly opened log. */
log_dump_context ();
}
else
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{
/* Eek! Opening the alternate log file has failed. Nothing we
can do but disable printing completely. */
fprintf (stderr, _("\n%s received.\n"), redirect_request_signal_name);
fprintf (stderr, _("%s: %s; disabling logging.\n"),
logfile, strerror (errno));
inhibit_logging = 1;
}
save_context_p = 0;
}
/* Check whether a signal handler requested the output to be
redirected. */
static void
check_redirect_output (void)
{
if (redirect_request == RR_REQUESTED)
{
redirect_request = RR_DONE;
redirect_output ();
}
}
/* Request redirection at a convenient time. This may be called from
a signal handler. */
void
log_request_redirect_output (const char *signal_name)
{
if (redirect_request == RR_NONE && save_context_p)
/* Request output redirection. The request will be processed by
check_redirect_output(), which is called from entry point log
functions. */
redirect_request = RR_REQUESTED;
redirect_request_signal_name = signal_name;
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}