ossp-pkg/l2/l2_ch_pipe.c
1.11
/*
** L2 - OSSP Logging Library
** Copyright (c) 2001 The OSSP Project (http://www.ossp.org/)
** Copyright (c) 2001 Cable & Wireless Deutschland (http://www.cw.com/de/)
**
** This file is part of OSSP L2, a flexible logging library which
** can be found at http://www.ossp.org/pkg/l2/.
**
** Permission to use, copy, modify, and distribute this software for
** any purpose with or without fee is hereby granted, provided that
** the above copyright notice and this permission notice appear in all
** copies.
**
** THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
** WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
** CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
** USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
** OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
** OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
** SUCH DAMAGE.
**
** l2_ch_pipe.c: pipe channel implementation
*/
#include "l2.h"
#include <unistd.h>
#include <signal.h>
#define L2_PIPE_MODEDIRECT 1 /* direct command execution */
#define L2_PIPE_MODESHELL 2 /* shell command execution */
#define L2_PIPE_MAXARGS 256 /* shell command execution */
/* declare private channel configuration */
typedef struct {
int piFd[2]; /* pipe file descriptor */
int iMode; /* execution mode direct or shell */
char *szCmdpath; /* path to command and arguments */
char *pVec[L2_PIPE_MAXARGS]; /* vector of command and params */
} l2_ch_pipe_t;
static void catchsignal(int sig, ...)
{
va_list ap;
static l2_ch_pipe_t *cfg = NULL;
va_start(ap, sig);
if (sig == 0)
cfg = va_arg(ap, l2_ch_pipe_t *);
else if (sig == SIGCHLD) {
fprintf(stderr, "Pipe: SIGCHLD caught\n");
close(cfg->piFd[1]);
cfg->piFd[1] = -1; /* TODO: Fill in with new pipe fd */
}
else if (sig == SIGPIPE) {
fprintf(stderr, "Pipe: SIGPIPE caught\n");
close(cfg->piFd[1]);
cfg->piFd[1] = -1; /* TODO: Fill in with new pipe fd */
/* ((l2_ch_pipe_t *)(int *)ctx->vp)->piFd[1] = -1; */
}
va_end(ap);
}
/* create channel */
static l2_result_t hook_create(l2_context_t *ctx, l2_channel_t *ch)
{
l2_ch_pipe_t *cfg;
/* allocate private channel configuration */
if ((cfg = (l2_ch_pipe_t *)malloc(sizeof(l2_ch_pipe_t))) == NULL)
return L2_ERR_ARG;
/* initialize configuration with reasonable defaults */
cfg->piFd[0] = -1;
cfg->piFd[1] = -1;
cfg->iMode = -1;
cfg->szCmdpath = NULL;
memset(cfg->pVec, 0, sizeof(cfg->pVec));
/* link private channel configuration into channel context */
ctx->vp = cfg;
return L2_OK;
}
/* configure channel */
static l2_result_t hook_configure(l2_context_t *ctx, l2_channel_t *ch, const char *fmt, va_list ap)
{
l2_ch_pipe_t *cfg = (l2_ch_pipe_t *)ctx->vp;
l2_param_t pa[3];
l2_result_t rv;
char szMode[16]; /* just eneough for double-byte "direct" and NULL */
/* feed and call generic parameter parsing engine */
L2_PARAM_SET(pa[0], mode, CHARPTR, szMode);
L2_PARAM_SET(pa[1], path, STRING, &cfg->szCmdpath);
L2_PARAM_END(pa[2]);
rv = l2_util_setparams(pa, fmt, ap);
if (strcmp(szMode, "direct") == NULL)
cfg->iMode = L2_PIPE_MODEDIRECT;
else if (strcmp(szMode, "shell") == NULL)
cfg->iMode = L2_PIPE_MODESHELL;
else
return L2_ERR_ARG;
catchsignal(0, cfg); /* initialize signal handler with incoming context */
signal(SIGCHLD, (void(*)())catchsignal); /* pipe changes descriptor */
signal(SIGPIPE, (void(*)())catchsignal); /* pipe closes reading fd */
return rv;
}
/**********************************************************
* parse_cmdpath: Helper method to hook_open *
* Parses szBuf into an argv-style string vector szArgs *
**********************************************************/
static l2_result_t parse_cmdpath (char *szBuf, char *szArgs[]) {
int iCnt = 0;
while ((iCnt++ < L2_PIPE_MAXARGS) && (*szBuf != NULL)) {
while ((*szBuf == ' ') || (*szBuf == '\t'))
*szBuf++ = '\0';
*szArgs++ = szBuf;
while ((*szBuf != '\0') && (*szBuf != ' ') && (*szBuf != '\t'))
szBuf++;
}
*szArgs = NULL;
if (iCnt <= L2_PIPE_MAXARGS)
return L2_OK;
else
return L2_ERR_ARG;
}
/**********************************************************
* child_exec: Helper method to hook_open *
* Redirect stdin to read from cfg->piFd. Exec a given *
* command or passes it to the sh shell for execution. *
**********************************************************/
static l2_result_t child_exec(l2_ch_pipe_t *cfg)
{
/* make sure a command path was set */
if (cfg->szCmdpath == NULL)
return L2_ERR_USE;
close(cfg->piFd[1]); /* close the writing end, */
cfg->piFd[1] = -1; /* because we don't use it */
dup2(cfg->piFd[0], fileno(stdin)); /* copy the reading end */
return execvp(*cfg->pVec, cfg->pVec); /* launch */
}
/* open channel */
static l2_result_t hook_open(l2_context_t *ctx, l2_channel_t *ch)
{
l2_ch_pipe_t *cfg = (l2_ch_pipe_t *)ctx->vp;
l2_result_t rv;
pid_t Pid;
if ((rv = parse_cmdpath(cfg->szCmdpath, cfg->pVec)) != L2_OK)
return rv;
if (pipe(cfg->piFd) == -1) /* open the pipe */
return L2_ERR_SYS;
if ((Pid = fork()) > 0) { /* parent process */
close(cfg->piFd[0]);
cfg->piFd[0] = -1;
}
else if ((Pid = fork()) == 0) { /* child process */
/* if child returns, there was an error */
if (child_exec(cfg) == -1) {
close(cfg->piFd[0]);
cfg->piFd[0] = -1;
return L2_ERR_SYS;
}
}
else /* fork failed */
return L2_ERR_SYS;
return L2_OK;
}
/* write to channel */
static l2_result_t hook_write(l2_context_t *ctx, l2_channel_t *ch,
l2_level_t level, const char *buf, size_t buf_size)
{
l2_ch_pipe_t *cfg = (l2_ch_pipe_t *)ctx->vp;
/* validate the pipe fd */
if (cfg->piFd[1] == -1) /* TODO: possibly remove this validation in */
return L2_ERR_ARG; /* lieu of incoming SIGPIPE signal */
/* write message to channel pipe */
if (write(cfg->piFd[1], buf, buf_size) == -1)
return L2_ERR_SYS;
return L2_OK;
}
/* close channel */
static l2_result_t hook_close(l2_context_t *ctx, l2_channel_t *ch)
{
l2_ch_pipe_t *cfg = (l2_ch_pipe_t *)ctx->vp;
/* close channel pipe for parent process created in hook_open() */
close(cfg->piFd[1]);
cfg->piFd[1] = -1;
return L2_OK;
}
/* destroy channel */
static l2_result_t hook_destroy(l2_context_t *ctx, l2_channel_t *ch)
{
l2_ch_pipe_t *cfg = (l2_ch_pipe_t *)ctx->vp;
/* destroy channel configuration */
free(&cfg->szCmdpath);
cfg->szCmdpath = NULL;
free(cfg);
return L2_OK;
}
/* exported channel handler structure */
l2_handler_t l2_handler_pipe = {
L2_CHANNEL_OUTPUT,
hook_create,
hook_configure,
hook_open,
hook_write,
NULL,
hook_close,
hook_destroy
};