/* filter.c: filter framework functions
*
* Copyright (C) 2006-2014 cgit Development Team <cgit@lists.zx2c4.com>
*
* Licensed under GNU General Public License v2
* (see COPYING for full license text)
*/
#include "cgit.h"
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <dlfcn.h>
static ssize_t (*libc_write)(int fd, const void *buf, size_t count);
static ssize_t (*filter_write)(struct cgit_filter *base, const void *buf, size_t count) = NULL;
static struct cgit_filter *current_write_filter = NULL;
static inline void reap_filter(struct cgit_filter *filter)
{
if (filter && filter->cleanup)
filter->cleanup(filter);
}
void cgit_cleanup_filters(void)
{
int i;
reap_filter(ctx.cfg.about_filter);
reap_filter(ctx.cfg.commit_filter);
reap_filter(ctx.cfg.source_filter);
for (i = 0; i < cgit_repolist.count; ++i) {
reap_filter(cgit_repolist.repos[i].about_filter);
reap_filter(cgit_repolist.repos[i].commit_filter);
reap_filter(cgit_repolist.repos[i].source_filter);
}
}
void cgit_init_filters(void)
{
libc_write = dlsym(RTLD_NEXT, "write");
if (!libc_write)
die("Could not locate libc's write function");
}
ssize_t write(int fd, const void *buf, size_t count)
{
if (fd != STDOUT_FILENO || !filter_write)
return libc_write(fd, buf, count);
return filter_write(current_write_filter, buf, count);
}
static inline void hook_write(struct cgit_filter *filter, ssize_t (*new_write)(struct cgit_filter *base, const void *buf, size_t count))
{
/* We want to avoid buggy nested patterns. */
assert(filter_write == NULL);
assert(current_write_filter == NULL);
current_write_filter = filter;
filter_write = new_write;
}
static inline void unhook_write()
{
assert(filter_write != NULL);
assert(current_write_filter != NULL);
filter_write = NULL;
current_write_filter = NULL;
}
static int open_exec_filter(struct cgit_filter *base, va_list ap)
{
struct cgit_exec_filter *filter = (struct cgit_exec_filter *) base;
int i;
for (i = 0; i < filter->base.argument_count; i++)
filter->argv[i+1] = va_arg(ap, char *);
filter->old_stdout = chk_positive(dup(STDOUT_FILENO),
"Unable to duplicate STDOUT");
chk_zero(pipe(filter->pipe_fh), "Unable to create pipe to subprocess");
filter->pid = chk_non_negative(fork(), "Unable to create subprocess");
if (filter->pid == 0) {
close(filter->pipe_fh[1]);
chk_non_negative(dup2(filter->pipe_fh[0], STDIN_FILENO),
"Unable to use pipe as STDIN");
execvp(filter->cmd, filter->argv);
die_errno("Unable to exec subprocess %s", filter->cmd);
}
close(filter->pipe_fh[0]);
chk_non_negative(dup2(filter->pipe_fh[1], STDOUT_FILENO),
"Unable to use pipe as STDOUT");
close(filter->pipe_fh[1]);
return 0;
}
static int close_exec_filter(struct cgit_filter *base)
{
struct cgit_exec_filter *filter = (struct cgit_exec_filter *) base;
int i, exit_status;
chk_non_negative(dup2(filter->old_stdout, STDOUT_FILENO),
"Unable to restore STDOUT");
close(filter->old_stdout);
if (filter->pid < 0)
goto done;
waitpid(filter->pid, &exit_status, 0);
if (WIFEXITED(exit_status) && !WEXITSTATUS(exit_status))
goto done;
die("Subprocess %s exited abnormally", filter->cmd);
done:
for (i = 0; i < filter->base.argument_count; i++)
filter->argv[i+1] = NULL;
return 0;
}
static void fprintf_exec_filter(struct cgit_filter *base, FILE *f, const char *prefix)
{
struct cgit_exec_filter *filter = (struct cgit_exec_filter *) base;
fprintf(f, "%sexec:%s\n", prefix, filter->cmd);
}
static void cleanup_exec_filter(struct cgit_filter *base)
{
struct cgit_exec_filter *filter = (struct cgit_exec_filter *) base;
if (filter->argv) {
free(filter->argv);
filter->argv = NULL;
}
if (filter->cmd) {
free(filter->cmd);
filter->cmd = NULL;
}
}
static struct cgit_filter *new_exec_filter(const char *cmd, int argument_count)
{
struct cgit_exec_filter *f;
int args_size = 0;
f = xmalloc(sizeof(*f));
/* We leave argv for now and assign it below. */
cgit_exec_filter_init(f, xstrdup(cmd), NULL);
f->base.argument_count = argument_count;
args_size = (2 + argument_count) * sizeof(char *);
f->argv = xmalloc(args_size);
memset(f->argv, 0, args_size);
f->argv[0] = f->cmd;
return &f->base;
}
void cgit_exec_filter_init(struct cgit_exec_filter *filter, char *cmd, char **argv)
{
memset(filter, 0, sizeof(*filter));
filter->base.open = open_exec_filter;
filter->base.close = close_exec_filter;
filter->base.fprintf = fprintf_exec_filter;
filter->base.cleanup = cleanup_exec_filter;
filter->cmd = cmd;
filter->argv = argv;
/* The argument count for open_filter is zero by default, unless called from new_filter, above. */
filter->base.argument_count = 0;
}
int cgit_open_filter(struct cgit_filter *filter, ...)
{
int result;
va_list ap;
va_start(ap, filter);
result = filter->open(filter, ap);
va_end(ap);
return result;
}
int cgit_close_filter(struct cgit_filter *filter)
{
return filter->close(filter);
}
void cgit_fprintf_filter(struct cgit_filter *filter, FILE *f, const char *prefix)
{
filter->fprintf(filter, f, prefix);
}
static const struct {
const char *prefix;
struct cgit_filter *(*ctor)(const char *cmd, int argument_count);
} filter_specs[] = {
{ "exec", new_exec_filter },
};
struct cgit_filter *cgit_new_filter(const char *cmd, filter_type filtertype)
{
char *colon;
int i;
size_t len;
int argument_count;
if (!cmd || !cmd[0])
return NULL;
colon = strchr(cmd, ':');
len = colon - cmd;
/*
* In case we're running on Windows, don't allow a single letter before
* the colon.
*/
if (len == 1)
colon = NULL;
switch (filtertype) {
case SOURCE:
case ABOUT:
argument_count = 1;
break;
case COMMIT:
default:
argument_count = 0;
break;
}
/* If no prefix is given, exec filter is the default. */
if (!colon)
return new_exec_filter(cmd, argument_count);
for (i = 0; i < ARRAY_SIZE(filter_specs); i++) {
if (len == strlen(filter_specs[i].prefix) &&
!strncmp(filter_specs[i].prefix, cmd, len))
return filter_specs[i].ctor(colon + 1, argument_count);
}
die("Invalid filter type: %.*s", (int) len, cmd);
}
