Backtick support to infinite (memory limited) levels of nesting is
now implemented... So now busybox shell can do cool stuff like:
/home/andersen/CVS/busybox # echo foo `wc README` bar
foo 71 422 2951 README bar
I love writing cool new features.... Muhahahaha... (I think this is
leaking a little bit of memory every time it expands a backtick process,
so I still needs to do a bit of cleanup...)
-Erik
diff --git a/shell/lash.c b/shell/lash.c
index 9b34353..1dfce9e 100644
--- a/shell/lash.c
+++ b/shell/lash.c
@@ -25,6 +25,11 @@
*
*/
+
+#define BB_FEATURE_SH_BACKTICKS
+
+
+
#include "internal.h"
#include <stdio.h>
#include <stdlib.h>
@@ -108,7 +113,7 @@
static int getCommand(FILE * source, char *command);
static int parseCommand(char **commandPtr, struct job *job, struct jobSet *jobList, int *isBg);
static int setupRedirections(struct childProgram *prog);
-static int runCommand(struct job *newJob, struct jobSet *jobList, int inBg);
+static int runCommand(struct job *newJob, struct jobSet *jobList, int inBg, int outPipe[2]);
static int busy_loop(FILE * input);
@@ -420,6 +425,10 @@
break;
}
+ /* This happens on backticked commands */
+ if(job==NULL)
+ return;
+
if (WIFEXITED(status) || WIFSIGNALED(status)) {
/* child exited */
job->runningProgs--;
@@ -697,7 +706,7 @@
if (*prog->argv[argc])
argc++;
if (!argc) {
- errorMsg("empty command in pipe1\n");
+ errorMsg("empty command in pipe\n");
freeJob(job);
job->numProgs=0;
return 1;
@@ -723,7 +732,7 @@
src++;
if (!*src) {
- errorMsg("empty command in pipe2\n");
+ errorMsg("empty command in pipe\n");
freeJob(job);
job->numProgs=0;
return 1;
@@ -749,12 +758,16 @@
if (*src == '*' || *src == '[' || *src == ']'
|| *src == '?') *buf++ = '\\';
/* fallthrough */
+#ifdef BB_FEATURE_SH_BACKTICKS
case '`':
/* Exec a backtick-ed command */
{
- char* newcmd=NULL;
+ char* charptr1=NULL, *charptr2;
char* ptr=NULL;
- struct job newJob;
+ struct job *newJob;
+ struct jobSet njobList = { NULL, NULL };
+ int pipefd[2];
+ int size;
ptr=strchr(++src, '`');
if (ptr==NULL) {
@@ -763,19 +776,56 @@
return 1;
}
- newcmd = xmalloc(1+ptr-src);
- snprintf(newcmd, 1+ptr-src, src);
+ /* Make a copy of any stuff left over in the command
+ * line after the second backtick */
+ charptr2 = xmalloc(strlen(ptr)+1);
+ memcpy(charptr2, ptr+1, strlen(ptr));
- if (!parseCommand(&newcmd, &newJob, jobList, isBg) &&
- newJob.numProgs) {
- runCommand(&newJob, jobList, *isBg);
+ /* Make some space to hold just the backticked command */
+ charptr1 = xmalloc(1+ptr-src);
+ snprintf(charptr1, 1+ptr-src, src);
+ newJob = xmalloc(sizeof(struct job));
+ /* Now parse and run the backticked command */
+ if (!parseCommand(&charptr1, newJob, &njobList, isBg)
+ && newJob->numProgs) {
+ pipe(pipefd);
+ runCommand(newJob, &njobList, 0, pipefd);
}
+ checkJobs(jobList);
+ free(charptr1);
- /* Clip out the the backticked command from the string */
- memmove(--src, ptr, strlen(ptr)+1);
- free(newcmd);
+ /* Copy the output from the backtick-ed command into the
+ * command line, making extra room as needed */
+ --src;
+ charptr1 = xmalloc(BUFSIZ);
+ while ( (size=fullRead(pipefd[0], charptr1, BUFSIZ-1)) >0) {
+ int newSize=src - *commandPtr + size + 1 + strlen(charptr2);
+ if (newSize > BUFSIZ) {
+ *commandPtr=realloc(*commandPtr, src - *commandPtr +
+ size + 1 + strlen(charptr2));
+ }
+ memcpy(src, charptr1, size);
+ src+=size;
+ }
+ free(charptr1);
+ close(pipefd[0]);
+ if (*(src-1)=='\n')
+ --src;
+
+ /* Now paste into the *commandPtr all the stuff
+ * leftover after the second backtick */
+ memcpy(src, charptr2, strlen(charptr2));
+ fprintf(stderr,"*commandPtr='%s'\n", *commandPtr);
+ free(charptr2);
+
+
+ /* Now recursively call parseCommand to deal with the new
+ * and improved version of the command line with the backtick
+ * results expanded in place... */
+ return(parseCommand(commandPtr, job, jobList, isBg));
}
break;
+#endif // BB_FEATURE_SH_BACKTICKS
default:
*buf++ = *src;
}
@@ -810,25 +860,23 @@
}
-static int runCommand(struct job *newJob, struct jobSet *jobList, int inBg)
+static int runCommand(struct job *newJob, struct jobSet *jobList, int inBg, int outPipe[2])
{
struct job *job;
+ int nextin=0, nextout, stdoutfd=fileno(stdout);
int i;
- int nextin, nextout;
int pipefds[2]; /* pipefd[0] is for reading */
struct builtInCommand *x;
#ifdef BB_FEATURE_SH_STANDALONE_SHELL
const struct BB_applet *a = applets;
#endif
-
- nextin = 0, nextout = 1;
for (i = 0; i < newJob->numProgs; i++) {
if ((i + 1) < newJob->numProgs) {
pipe(pipefds);
nextout = pipefds[1];
} else {
- nextout = 1;
+ nextout = stdoutfd;
}
/* Check if the command matches any non-forking builtins */
@@ -841,16 +889,17 @@
if (!(newJob->progs[i].pid = fork())) {
signal(SIGTTOU, SIG_DFL);
- if (nextin != 0) {
- dup2(nextin, 0);
- close(nextin);
- }
-
- if (nextout != 1) {
+ if (outPipe[1]!=-1) {
+ close(outPipe[0]);
+ nextout = stdoutfd = outPipe[1];
dup2(nextout, 1);
+ dup2(nextout, 2);
close(nextout);
}
+ //dup2(nextin, 0);
+ //close(nextin);
+
/* explicit redirections override pipes */
setupRedirections(newJob->progs + i);
@@ -862,8 +911,8 @@
}
#ifdef BB_FEATURE_SH_STANDALONE_SHELL
/* Check if the command matches any busybox internal commands here */
- /* TODO: Add matching when paths are appended (i.e. 'cat' currently
- * works, but '/bin/cat' doesn't ) */
+ /* TODO: Add matching on commands with paths appended (i.e. 'cat'
+ * currently works, but '/bin/cat' doesn't ) */
while (a->name != 0) {
if (strcmp(newJob->progs[i].argv[0], a->name) == 0) {
int argc;
@@ -879,6 +928,9 @@
fatalError("%s: %s\n", newJob->progs[i].argv[0],
strerror(errno));
}
+ if (outPipe[1]!=-1) {
+ close(outPipe[1]);
+ }
/* put our child in the process group whose leader is the
first process in this pipe */
@@ -886,7 +938,7 @@
if (nextin != 0)
close(nextin);
- if (nextout != 1)
+ if (nextout != stdoutfd)
close(nextout);
/* If there isn't another process, nextin is garbage
@@ -1007,9 +1059,12 @@
if (!parseCommand(&nextCommand, &newJob, &jobList, &inBg) &&
newJob.numProgs) {
- runCommand(&newJob, &jobList, inBg);
+ int pipefds[2] = {-1,-1};
+ runCommand(&newJob, &jobList, inBg, pipefds);
} else {
nextCommand=NULL;
+ free(command);
+ command = (char *) calloc(BUFSIZ, sizeof(char));
}
} else {
/* a job is running in the foreground; wait for it */