Implement xargs (first pass, not full SUSv4 yet).

1 files changed, 174 insertions, 0 deletions

diff --git a/toys/xargs.c b/toys/xargs.c
new file mode 100644
index 00000000..67e88cfc
--- /dev/null
+++ b/toys/xargs.c
@@ -0,0 +1,174 @@
+/* vi: set sw=4 ts=4:
+ *
+ * xargs.c - Run command with arguments taken from stdin.
+ *
+ * Copyright 2011 Rob Landley <rob@landley.net>
+ *
+ * See http://opengroup.org/onlinepubs/9699919799/utilities/xargs.html
+
+USE_XARGS(NEWTOY(xargs, "n#s#0", TOYFLAG_USR|TOYFLAG_BIN))
+
+config XARGS
+	bool "xargs"
+	default y
+	help
+	  usage: xargs [-ptxr0] [-s NUM] [-n NUM] [-L NUM] [-E STR] COMMAND...
+
+	  Run command line one or more times, appending arguments from stdin.
+
+	  -s	Size in bytes per command line
+	  -n	Max number of arguments per command
+	  -0	Each argument is NULL terminated, no whitespace or quote processing
+*/
+
+#include "toys.h"
+
+DEFINE_GLOBALS(
+	long max_bytes;
+	long max_entries;
+	long L;
+	char *E;
+	char *I;
+
+	long entries, bytes;
+	char delim;
+)
+
+#define TT this.xargs
+
+// According to man execv(5), the actual ARGS_MAX for linux is 128k (131072)
+// meaning the theoretical maximum arguments (each one char) is 65536... but
+// we can just use toybuf (1024 pointer on 32 bit, 512 on 64 bit).
+
+#define ACTUAL_ARGS_MAX 131072
+
+// If out==NULL count TT.bytes and TT.entries, stopping at max.
+// Otherwise, fill out out[] 
+
+// Returning NULL means need more data.
+// Returning 1 means hit data limits, but consumed all data
+// Returning char * means hit data limits, start of data left over
+
+static char *handle_entries(char *data, char **entry)
+{
+	if (TT.delim) { 
+		char *s = data;
+
+		// Chop up whitespace delimited string into args
+		while (*s) {
+			char *save;
+
+			while (isspace(*s)) {
+				if (entry) *s = 0;
+				s++;
+			}
+
+			if (TT.entries >= TT.max_entries && TT.max_entries)
+				return *s ? (char *)1: s;
+
+			if (!*s) break;
+			save = s;
+
+			for (;;) {
+				if (++TT.bytes >= TT.max_bytes && TT.max_bytes) return save;
+				if (!*s || isspace(*s)) break;
+				s++;
+			}
+			if (entry) entry[TT.entries] = save;
+			++TT.entries;
+		}
+	} else {
+		if (entry) entry[TT.entries] = data;
+		TT.bytes += strlen(data);
+		if (TT.bytes >= TT.max_bytes || ++TT.entries >= TT.max_entries)
+			return (char *)1;
+	}
+
+	return NULL;
+}
+
+void xargs_main(void)
+{
+	struct double_list *dlist = NULL;
+	int entries, bytes, done = 0, status;
+	char *data = NULL;
+
+	if (!(toys.optflags&1)) TT.delim = '\n';
+
+	// If no optargs, call echo.
+	if (!toys.optc) {
+		free(toys.optargs);
+		*(toys.optargs=xzalloc(2*sizeof(char *)))="echo";
+		toys.optc=1;
+	}
+
+	for (entries = 0, bytes = -1; entries < toys.optc; entries++, bytes++)
+		bytes += strlen(toys.optargs[entries]);
+
+	// Loop through exec chunks.
+	while (!done) {
+		TT.entries = 0;
+		TT.bytes = bytes;
+		char **out;
+
+		// Loop reading input
+		for (;;) {
+
+			// Read line
+			if (!data) {
+				ssize_t l = 0;
+				l = getdelim(&data, (size_t *)&l, TT.delim, stdin);
+
+				if (l<0) {
+					data = 0;
+					done++;
+					break;
+				}
+			}
+			dlist_add(&dlist, data);
+
+			// Count data used
+			data = handle_entries(data, NULL);
+			if (!data) continue;
+			if (data == (char *)1) data = 0;
+			else data = xstrdup(data);
+
+			break;
+		}
+
+		// Accumulate cally thing
+
+		if (data && !TT.entries) error_exit("argument too long");
+		out = xzalloc((entries+TT.entries+1)*sizeof(char *));
+
+		if (dlist) {
+			struct double_list *dtemp;
+
+			// Fill out command line to exec
+			memcpy(out, toys.optargs, entries*sizeof(char *));
+			TT.entries = 0;
+			TT.bytes = bytes;
+			dlist->prev->next = 0;
+			for (dtemp = dlist; dtemp; dtemp = dtemp->next)
+				handle_entries(dtemp->data, out+entries);
+		}
+		pid_t pid=fork();
+		if (!pid) {
+			xclose(0);
+			open("/dev/null", O_RDONLY);
+			xexec(out);
+		}
+		waitpid(pid, &status, 0);
+		status = WEXITSTATUS(status);
+
+		// Abritrary number of execs, can't just leak memory each time...
+		while (dlist) {
+			struct double_list *dtemp = dlist->next;
+
+			free(dlist->data);
+			free(dlist);
+			dlist = dtemp;
+		}
+		free(out);
+	}
+}