Added xargs utility, Added -std=c99 flag

1 files changed, 228 insertions, 0 deletions

diff --git a/src/xargs.c b/src/xargs.c
new file mode 100644
index 0000000..9c2a5e6
--- /dev/null
+++ b/src/xargs.c
@@ -0,0 +1,228 @@
+#define _POSIX_C_SOURCE 200809L
+#define _DEFAULT_SOURCE 1
+
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <stdbool.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <string.h>
+#include <sys/wait.h>
+
+static char   *g_eofstr    = NULL;
+static char   *g_replstr   = NULL;
+static size_t g_line_count = -1;
+static size_t g_arg_count  = -1;
+static bool   g_prompt     = false;
+static size_t g_size       = -1;
+static bool   g_trace      = false;
+static bool   g_terminate  = false;
+
+static char   *g_name      = "xargs";
+
+void die(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	fprintf(stderr, "%s: ", g_name);
+	vfprintf(stderr, fmt, ap);
+	fputc('\n', stderr);
+	va_end(ap);
+	exit(1);
+}
+
+void *xmalloc(size_t size)
+{
+	void *ret = malloc(size);
+	if (ret == NULL)
+		die(strerror(errno));
+	return ret;
+}
+
+char *xstrdup(const char *src)
+{
+	char *ret = strdup(src);
+	if (ret == NULL)
+		die(strerror(errno));
+	return ret;
+}
+
+size_t parse_uint(const char *optarg)
+{
+	unsigned long n;
+	char          *end;
+
+	errno = 0;
+	n = strtoul(optarg, &end, 10);
+	if (!isdigit(*optarg) || errno != 0 || *end != '\0')
+		die("invalid number \"%s\"", optarg);
+	return n;
+}
+
+size_t args_len(char **args)
+{
+	size_t	len;
+	for (len = 0; args[len] != NULL; len++);
+	return len;
+}
+
+void args_free(char **args)
+{
+	for (size_t i = 0; args[i] != NULL; i++)
+		free(args[i]);
+	free(args);
+}
+
+char **args_cpy(char **dst, char **src)
+{
+	size_t i;
+
+	for (i = 0; src[i] != NULL; i++)
+		dst[i] = xstrdup(src[i]);
+	dst[i] = NULL;
+	return dst;
+}
+
+char **args_dup(char **src)
+{
+	char **ret = xmalloc((args_len(src) + 1) * sizeof(char*));
+	return args_cpy(ret, src);
+}
+
+int main(int argc, char **argv)
+{
+	int option;
+
+	while ((option = getopt(argc, argv, "E:I:L:n:ps:tx")) > 0)
+	{
+		switch (option)
+		{
+			case 'E': g_eofstr     = optarg;             break;
+			case 'I': g_replstr    = optarg;             break;
+			case 'L': g_line_count = parse_uint(optarg); break;
+			case 'n': g_arg_count  = parse_uint(optarg); break;
+			case 'p': g_prompt     = true;               break;
+			case 's': g_size       = parse_uint(optarg); break;
+			case 't': g_trace      = true;               break;
+			case 'x': g_terminate  = true;               break;
+		}
+	}
+	if (g_line_count == 0)
+		die("value 0 for -L option should be >= 1");
+	if (g_arg_count == 0)
+		die("value 0 for -n option should be >= 1");
+	if (g_prompt)
+		g_trace = true;
+
+	char *cmd = optind != argc ? argv[optind] : "echo";
+	char **args_prefix;
+	if (optind == argc || optind + 1 == argc)
+	{
+		args_prefix = xmalloc(2 * sizeof(char*));
+		args_prefix[0] = cmd;
+		args_prefix[1] = NULL;
+	}
+	else
+	{
+		size_t len = argc - optind;
+		args_prefix = xmalloc((len + 1) * sizeof(char*));
+		size_t i;
+		for (i = 0; i < len; i++)
+			args_prefix[i] = argv[optind + i];
+		args_prefix[len] = NULL;
+	}
+
+	size_t len;
+	bool eof = false;
+	size_t command_count = 0;
+	while (!eof)
+	{
+		char   **args = args_dup(args_prefix);
+		char   *line = NULL;
+		size_t line_size = 0;
+		size_t count = 0;
+
+		while (getline(&line, &line_size, stdin) > 0)
+		{
+			// removing newline
+			char *last = line + strlen(line) - 1;
+			if (*last == '\n')
+				*last = '\0';
+			// trim blank characters
+			while (isblank(*line))
+				memmove(line, line + 1, strlen(line));
+			len = strlen(line);
+			while (len > 0 && isblank(line[len - 1]))
+			{
+				line[len - 1] = '\0';
+				len--;
+			}
+			// skipping blank lines
+			if (*line == '\0')
+				continue;
+			// stopping if eof string encountered
+			if (g_eofstr != NULL && strcmp(g_eofstr, line) == 0)
+			{
+				eof = true;
+				break;
+			}
+			// add line to arguments
+			len = args_len(args);
+			char **new_args = xmalloc((len + 2) * sizeof(char*));
+			args_cpy(new_args, args);
+			new_args[len] = xstrdup(line);
+			new_args[len + 2] = NULL;
+			/* args_free(args); */
+			args = new_args;
+			count++;
+			if ((g_line_count != (size_t)-1 && count >= g_line_count) ||
+				(g_arg_count != (size_t)-1  && count >= g_arg_count))
+				break;
+		}
+		if (feof(stdin))
+			eof = true;
+		if (eof && command_count != 0 && !g_prompt)
+			break;
+		command_count++;
+
+		pid_t child_pid;
+		child_pid = fork();
+		switch (child_pid)
+		{
+			case -1:
+				die(strerror(errno));
+				break;
+			case 0:
+				if (g_trace)
+					for (size_t i = 0; args[i] != NULL; i++)
+					{
+						fputs(args[i], stderr);
+						if (args[i + 1] != NULL)
+							fputc(' ', stderr);
+					}
+				bool confirmation = true;
+				if (g_prompt)
+				{
+					FILE *tty_file = fopen("/dev/tty", "r");
+					if (tty_file == NULL)
+						die("Couldn't open tty file");
+					fputs(" ?...", stderr);
+					int c = fgetc(tty_file);
+					confirmation = c == 'y' || c == 'Y';
+				}
+				else if (g_trace)
+					fputc('\n', stderr);
+				if (!confirmation)
+					exit(0);
+				execvp(cmd, args);
+				die(strerror(errno));
+		}
+		waitpid(child_pid, &child_pid, 0);
+		if (WEXITSTATUS(child_pid) == 255)
+			break;
+	}
+	return 0;
+}