Added a simple shell, jsh

3 files changed, 96 insertions, 0 deletions

diff --git a/src/cmd/jsh/README.md b/src/cmd/jsh/README.md
new file mode 100755
index 0000000..db638ed
--- /dev/null
+++ b/src/cmd/jsh/README.md
@@ -0,0 +1,3 @@
+#J-Shell (jsh)
+
+J-Shell is a simple unix shell written in C.
diff --git a/src/cmd/jsh/jsh.c b/src/cmd/jsh/jsh.c
new file mode 100755
index 0000000..320a93d
--- /dev/null
+++ b/src/cmd/jsh/jsh.c
@@ -0,0 +1,81 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <ctype.h>
+
+size_t getargs(const size_t n, char *args[n], FILE * const stream);
+int shellexec(size_t n, char * const args[n]);
+
+static bool run = true;
+
+int main(int argc, char *argv[]) {
+	char *words[BUFSIZ] = {NULL};
+	FILE *fp = stdin;
+	size_t numberofwords = 0;
+	if (argc == 2) {
+		if ((fp = fopen(argv[1], "r")) == NULL) {
+			perror("jsh");
+			return EXIT_FAILURE;
+		}
+	}
+	while (run) {
+		printf("$ ");
+		numberofwords = getargs(BUFSIZ, words, fp);
+		shellexec(BUFSIZ, words);
+		for (int i = 0; i < numberofwords; i++) {
+			free(words[i]);
+			words[i] = NULL;
+		}
+	}
+	return 0;
+}
+
+size_t getargs(const size_t n, char *args[n], FILE * const stream) {
+	size_t i = 0;
+	char c = 0, s[BUFSIZ], *sp = s;
+	memset(s, '\0', sizeof(s));
+	while ((c = fgetc(stream)) != EOF && i < n && sp < s + BUFSIZ) {
+		if (isspace(c)) {
+			*sp = '\0';
+			args[i++] = strdup(s);
+			sp = s;
+			if (strcmp(args[i-1], "") == 0) {
+				free(args[i-1]);
+				args[i-1] = NULL;
+				i--;
+			}
+			if (c == '\n') {
+				break;
+			}
+		} else {
+			*sp++ = c;
+		}
+	}
+	return i;
+}
+
+int shellexec(size_t n, char * const args[n]) {
+	if (strcmp(args[0], "exit") == 0) {
+		run = false;
+		return 0;
+	}
+	pid_t pid = fork();
+	int status;
+	if (pid == 0) {
+		if (execvp(args[0], args) == -1) {
+			perror("jsh");
+		}
+		exit(EXIT_FAILURE);
+	} else if (pid < 0) {
+		perror("jsh");
+		exit(EXIT_FAILURE);
+	} else {
+		do {
+		  waitpid(pid, &status, WUNTRACED);
+		} while (!WIFEXITED(status) && !WIFSIGNALED(status));
+	}
+	return 0;
+}
+
diff --git a/src/cmd/jsh/makefile b/src/cmd/jsh/makefile
new file mode 100755
index 0000000..72d7d68
--- /dev/null
+++ b/src/cmd/jsh/makefile
@@ -0,0 +1,12 @@
+CFLAGS=-Wall -Werror
+
+build: jsh
+	@cp jsh $(PROROOT)/build/bin/jsh
+
+jsh: jsh.c
+	$(CC) $(CFLAGS) -o jsh jsh.c
+
+clean:
+	@rm -r jsh
+
+.PHONY: build clean