--- l2_ch_pipe.c 2001/09/20 16:26:56 1.13
+++ l2_ch_pipe.c 2001/09/21 17:32:08 1.14
@@ -28,6 +28,7 @@
*/
#include "l2.h"
+#include "l2_p.h" /* for TRACE() */
#include <unistd.h>
#include <signal.h>
@@ -37,55 +38,36 @@
#define L2_PIPE_MODESHELL 2 /* shell command execution */
#define L2_PIPE_MAXARGS 256 /* shell command execution */
-static l2_result_t hook_open(l2_context_t *, l2_channel_t *); /* prototypes */
-static l2_result_t hook_close(l2_context_t *, l2_channel_t *);
+static l2_result_t hook_close(l2_context_t *, l2_channel_t *); /* prototypes */
/* declare private channel configuration */
typedef struct {
- int piFd[2]; /* pipe file descriptor */
- int iChild; /* exception status of child pipe process */
- int iMode; /* execution mode direct or shell */
- pid_t Pid; /* pid set during fork in hook_open() */
- char *szCmdpath; /* path to command and arguments */
+ pid_t Pid; /* process id of child command */
+ int iWritefail; /* counter to failed write() operations */
+ int piFd[2]; /* pipe file descriptor */
+ int iMode; /* execution mode direct or shell */
+ char *szCmdpath; /* path to command and arguments */
+ struct sigaction sigchld; /* initial state of chld signal handler */
+ struct sigaction sigpipe; /* initial state of pipe signal handler */
} l2_ch_pipe_t;
static void catchsignal(int sig, ...)
{
- va_list ap = NULL;
- static l2_context_t *ctx = NULL;
- static l2_channel_t *chan = NULL;
-
- if (sig == 0) {
- va_start(ap, sig);
- ctx = va_arg(ap, l2_context_t *);
- chan = va_arg(ap, l2_channel_t *);
- va_end(ap);
- }
- else if (sig == SIGCHLD) {
-/* TRACE("SIGCHLD caught\n");*/
- waitpid(((l2_ch_pipe_t *)ctx->vp)->Pid, &((l2_ch_pipe_t *)ctx->vp)->iChild, WUNTRACED);
- if (WIFEXITED(((l2_ch_pipe_t *)ctx->vp)->iChild)) {
- close(((l2_ch_pipe_t *)ctx->vp)->piFd[1]);
- ((l2_ch_pipe_t *)ctx->vp)->piFd[1] = -1;
- ((l2_ch_pipe_t *)ctx->vp)->Pid = -1;
- /* check if process called exit() abnormally, then if so restarts */
- if (WEXITSTATUS(((l2_ch_pipe_t *)ctx->vp)->iChild)) {
- fprintf(stderr, "exit status is %d\n", WEXITSTATUS(((l2_ch_pipe_t *)ctx->vp)->iChild));
- if (hook_open(ctx, chan) != L2_OK) { /* TODO: Fix infinit loop! */
- close(((l2_ch_pipe_t *)ctx->vp)->piFd[1]);
- ((l2_ch_pipe_t *)ctx->vp)->piFd[1] = -1;
- }
- }
- }
- else if (WIFSTOPPED(((l2_ch_pipe_t *)ctx->vp)->iChild)) {
- }
- }
- else if (sig == SIGPIPE) { /* thrown when we write to child's closed pipe */
-/* TRACE("SIGPIPE caught\n");*/
- close(((l2_ch_pipe_t *)ctx->vp)->piFd[1]);
- ((l2_ch_pipe_t *)ctx->vp)->piFd[1] = -1;
+ pid_t Pid; /* for wait() */
+ int iStatus = 0; /* for wait() */
+
+ if (sig == SIGCHLD) {
+ TRACE("SIGCHLD caught\n");
+ Pid = waitpid(-1, &iStatus, WUNTRACED);
+ if (WIFEXITED(iStatus))
+ TRACE("EXITED child\n"); /* child finished and returned */
+ else if (WIFSIGNALED(iStatus))
+ TRACE("SIGNALED child\n"); /* child finished due to a signal */
+ else if (WIFSTOPPED(iStatus))
+ TRACE("STOPPED child\n"); /* child stopped due to a signal */
}
+ else if (sig == SIGPIPE); /* noop for now */
}
/* create channel */
@@ -98,12 +80,14 @@
return L2_ERR_ARG;
/* initialize configuration with reasonable defaults */
- cfg->piFd[0] = -1;
- cfg->piFd[1] = -1;
- cfg->iChild = 0;
- cfg->iMode = -1;
- cfg->Pid = -1;
- cfg->szCmdpath = NULL;
+ cfg->Pid = -1;
+ cfg->iWritefail = 0;
+ cfg->piFd[0] = -1;
+ cfg->piFd[1] = -1;
+ cfg->iMode = -1;
+ cfg->szCmdpath = NULL;
+ memset(&cfg->sigchld, 0, sizeof(cfg->sigchld));
+ memset(&cfg->sigpipe, 0, sizeof(cfg->sigpipe));
/* link private channel configuration into channel context */
ctx->vp = cfg;
@@ -135,10 +119,10 @@
else
return L2_ERR_ARG;
- /* check to see if a file exists at the user specified path */
- if(cfg->iMode != L2_PIPE_MODESHELL) {
+ /* check to see if a file exists at the user specified path */
+ if (cfg->iMode != L2_PIPE_MODESHELL) {
szTemp = strdup(cfg->szCmdpath);
- for (pbIndex = szTemp; *pbIndex != NULL; pbIndex++);
+ for (pbIndex = szTemp; (*pbIndex != ' ') && (*pbIndex != NULL); pbIndex++);
*pbIndex = NULL;
if (!(File = fopen(szTemp, "r")))
return L2_ERR_ARG; /* the command does not exist at the given path */
@@ -149,11 +133,7 @@
pbIndex = NULL;
}
- catchsignal(0, ctx, ch); /* initialize signal handler with context & ch */
- signal(SIGCHLD, (void(*)())catchsignal); /* pipe changes descriptor */
- signal(SIGPIPE, (void(*)())catchsignal); /* pipe closes reading fd */
-
- return rv; /* all okay */
+ return rv;
}
/**********************************************************
@@ -163,6 +143,9 @@
static l2_result_t parse_cmdpath (char *szBuf, char *szArgs[]) {
int iCnt = 0;
+ if (szBuf == NULL) /* check for bad input before we */
+ return L2_ERR_ARG; /* dereference and throw a SIGSEV */
+
while ((iCnt++ < L2_PIPE_MAXARGS) && (*szBuf != NULL)) {
while ((*szBuf == ' ') || (*szBuf == '\t'))
*szBuf++ = '\0'; /* overwrite whitespace with EOL */
@@ -183,13 +166,22 @@
{
l2_ch_pipe_t *cfg = (l2_ch_pipe_t *)ctx->vp;
char *pVec[L2_PIPE_MAXARGS];
+ struct sigaction locact;
l2_result_t rv;
- /* make sure a command path was set */
- if (cfg->szCmdpath == NULL)
- return L2_ERR_USE;
-
+ /* initialize auto vars before using them */
memset(pVec, 0, sizeof(pVec));
+ memset(&locact, 0, sizeof(locact));
+
+ locact.sa_handler = (void(*)())catchsignal;
+ sigemptyset(&locact.sa_mask);
+ locact.sa_flags = 0;
+
+ /* save old signal context before replacing with our own */
+ if (sigaction(SIGCHLD, &locact, &cfg->sigchld) < 0)
+ return L2_ERR_SYS;
+ if (sigaction(SIGPIPE, &locact, &cfg->sigpipe) < 0)
+ return L2_ERR_SYS;
/* the distinction between modes is necessary, because only executing */
/* commands in a shell environment allows usage of variables and such */
@@ -200,7 +192,7 @@
pVec[3] = NULL; /* add a NULL to mark the end of the chain */
}
- else /* plain command execution */
+ else /* plain direct command execution */
if ((rv = parse_cmdpath(cfg->szCmdpath, pVec)) != L2_OK)
return rv;
@@ -217,8 +209,8 @@
dup2(cfg->piFd[0], fileno(stdin)); /* copy the reading end */
if (execvp(*pVec, pVec) == -1) { /* launch */
- close(cfg->piFd[0]); /* cleanup */
- cfg->piFd[0] = -1;
+ close(cfg->piFd[0]); /* cleanup in case we fail */
+ cfg->piFd[0] = -1; /* if execvp() doesn't swap our context or */
return L2_ERR_SYS; /* if child returns, we have an error */
}
}
@@ -228,27 +220,28 @@
return L2_OK;
}
-/* write to channel */
+/* write to channel, possibly recursively */
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;
- if (cfg->piFd[1] == -1)
- return L2_ERR_IO;
-
- if (WIFSTOPPED(cfg->iChild)) {
- if (kill(cfg->Pid, SIGCONT)) {
+ /* write message to channel pipe */
+ if (write(cfg->piFd[1], buf, buf_size) == -1) {
+ if ((errno == EPIPE) && (cfg->iWritefail++ < 6)) {
hook_close(ctx, ch);
- cfg->iChild = 0;
+ hook_open(ctx, ch);
+ return hook_write(ctx, ch, level, buf, buf_size);
+ }
+ else { /* not broken pipe problem or over the fail limit */
+ cfg->iWritefail = 0; /* reset pipe failure counter */
return L2_ERR_SYS;
}
}
- /* write message to channel pipe */
- else if (write(cfg->piFd[1], buf, buf_size) == -1)
- return L2_ERR_SYS;
-
- return L2_OK;
+ else { /* write() to pipe succeeded */
+ cfg->iWritefail = 0; /* reset pipe failure counter */
+ return L2_OK;
+ }
}
/* close channel */
@@ -256,13 +249,19 @@
{
l2_ch_pipe_t *cfg = (l2_ch_pipe_t *)ctx->vp;
+ /* restore previous signal context */
+ if (sigaction(SIGCHLD, &cfg->sigchld, NULL) < 0)
+ return L2_ERR_SYS;
+ if (sigaction(SIGPIPE, &cfg->sigpipe, NULL) < 0)
+ return L2_ERR_SYS;
+
/* close channel pipe for parent process created in hook_open() */
close(cfg->piFd[1]);
cfg->piFd[1] = -1;
- if (kill(cfg->Pid, SIGTERM))
+ if ((kill (cfg->Pid, SIGTERM)) && (errno != ESRCH))
return L2_ERR_SYS;
- cfg->Pid = -1;
+ cfg->Pid = -1;
return L2_OK;
}
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