Hi,
This is a quick hack implementing xargs(1). Many features
are currently missing and there is a known issue with overflowing
the `argb' buffer.
Any comments?
bye,
sin
>From 731875ba179abbe8604d8979510195fa8d85ac20 Mon Sep 17 00:00:00 2001
From: sin <s...@2f30.org>
Date: Fri, 3 Jan 2014 11:52:47 +0000
Subject: [PATCH] Add initial version of xargs(1)
---
Makefile | 1 +
xargs.c | 213 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 214 insertions(+)
create mode 100644 xargs.c
diff --git a/Makefile b/Makefile
index 2a72a1c..81dfaf6 100644
--- a/Makefile
+++ b/Makefile
@@ -93,6 +93,7 @@ SRC = \
stat.c \
wc.c \
who.c \
+ xargs.c \
yes.c
OBJ = $(SRC:.c=.o) $(LIB)
diff --git a/xargs.c b/xargs.c
new file mode 100644
index 0000000..72159ef
--- /dev/null
+++ b/xargs.c
@@ -0,0 +1,213 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include "text.h"
+#include "util.h"
+
+static int inputc(void);
+static void deinputc(int);
+static void eatspace(void);
+static char *poparg(void);
+static int parsesquote(void);
+static int parsedquote(void);
+static char *poparg(void);
+static void pusharg(char *);
+static int runcmd(void);
+
+static void
+usage(void)
+{
+ eprintf("usage: %s [-r] [cmd [arg...]]", argv0);
+}
+
+static char **cmd;
+static char argb[BUFSIZ];
+static size_t argbpos;
+static int rflag = 0;
+
+int
+main(int argc, char *argv[])
+{
+ char *arg;
+ int i = 0;
+
+ ARGBEGIN {
+ case 'r':
+ rflag = 1;
+ break;
+ default:
+ usage();
+ } ARGEND;
+
+ cmd = malloc(sysconf(_SC_ARG_MAX) * sizeof(*cmd));
+ if (!cmd)
+ eprintf("malloc:");
+
+ do {
+ if (argc > 0)
+ for (i = 0; i < argc; i++)
+ cmd[i] = strdup(argv[i]);
+ else
+ cmd[i++] = strdup("/bin/echo");
+ while ((arg = poparg())) {
+ if (i < sysconf(_SC_ARG_MAX) - 1) {
+ cmd[i++] = strdup(arg);
+ } else {
+ pusharg(arg);
+ break;
+ }
+ }
+ cmd[i] = NULL;
+ runcmd();
+ for (; i >= 0; i--)
+ free(cmd[i]);
+ } while (arg);
+
+ free(cmd);
+ return 0;
+}
+
+static int
+inputc(void)
+{
+ int ch;
+
+ ch = getc(stdin);
+ if (ch == EOF && ferror(stdin))
+ eprintf("stdin: read error:");
+ return ch;
+}
+
+static void
+deinputc(int ch)
+{
+ ungetc(ch, stdin);
+}
+
+static void
+eatspace(void)
+{
+ int ch;
+
+ while ((ch = inputc()) != EOF) {
+ switch (ch) {
+ case ' ': case '\t': case '\n':
+ break;
+ default:
+ deinputc(ch);
+ return;
+ }
+ }
+}
+
+static int
+parsesquote(void)
+{
+ int ch;
+ int ok = -1;
+
+ while ((ch = inputc()) != EOF) {
+ switch (ch) {
+ case '\'':
+ argb[argbpos] = '\0';
+ ok = 0;
+ break;
+ default:
+ if (ch != '\n')
+ argb[argbpos++] = ch;
+ break;
+ }
+ }
+ return ok;
+}
+
+static int
+parsedquote(void)
+{
+ int ch;
+ int ok = -1;
+
+ while ((ch = inputc()) != EOF) {
+ switch (ch) {
+ case '\"':
+ argb[argbpos] = '\0';
+ ok = 0;
+ break;
+ default:
+ if (ch != '\n')
+ argb[argbpos++] = ch;
+ break;
+ }
+ }
+ return ok;
+}
+
+static char *
+poparg(void)
+{
+ int ch;
+ int escape = 0;
+
+ argbpos = 0;
+ eatspace();
+ while ((ch = inputc()) != EOF) {
+ switch (ch) {
+ case ' ': case '\t': case '\n':
+ if (escape == 1) {
+ escape = !escape;
+ if (ch != '\n') {
+ argb[argbpos++] = ch;
+ break;
+ }
+ }
+ argb[argbpos] = '\0';
+ deinputc(ch);
+ return argb;
+ case '\'':
+ if (parsesquote() == -1)
+ enprintf(EXIT_FAILURE, "unterminated quote\n");
+ break;
+ case '\"':
+ if (parsedquote() == -1)
+ enprintf(EXIT_FAILURE, "unterminated quote\n");
+ break;
+ case '\\':
+ escape = !escape;
+ break;
+ default:
+ argb[argbpos++] = ch;
+ break;
+ }
+ }
+ if (argbpos > 0) {
+ argb[argbpos] = '\0';
+ return argb;
+ }
+ return NULL;
+}
+
+static void
+pusharg(char *arg)
+{
+ char *p;
+
+ for (p = &arg[strlen(arg) - 1]; p >= arg; p--)
+ deinputc(*p);
+}
+
+static int
+runcmd(void)
+{
+ pid_t pid;
+
+ pid = fork();
+ if (pid < 0)
+ eprintf("fork:");
+ if (pid == 0)
+ execvp(*cmd, cmd);
+ wait(NULL);
+ return 0;
+}
--
1.8.4.5
