From f959165cdece3c1bfae8abce834a2bb78db96190 Mon Sep 17 00:00:00 2001
From: Stefan Zabka <zabkaste@hu-berlin.de>
Date: Thu, 21 May 2020 23:37:38 +0200
Subject: Process parse_line working

---
 02_exercise/process.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 02_exercise/process.c

(limited to '02_exercise/process.c')

diff --git a/02_exercise/process.c b/02_exercise/process.c
new file mode 100644
index 0000000..9bc85be
--- /dev/null
+++ b/02_exercise/process.c
@@ -0,0 +1,148 @@
+//
+// Created by stefan on 21.05.20.
+//
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <wait.h>
+
+#include "array.h"
+#include "process.h"
+
+// Given a substring of a line tries to parse out as much information as possible
+int parse_command(char const *line, char const *end, process *p) {
+
+    char *part;
+    char **local_parts;
+    if (arrayInit(part) != 0 || arrayInit(local_parts) != 0) {
+        fprintf(stderr, "Failed to prepare new part / parts array whilst parsing line");
+        return -1;
+    }
+
+    for (size_t i = 0; line + i < end; ++i) {
+        char c = line[i];
+        if (c == ' ' || c == '\0') {
+            if (arrayLen(part) == 0)
+                continue;
+            arrayPush(part) = '\0';
+            arrayPush(local_parts) = part;
+            if (c == '\0') {
+                arrayPush(local_parts) = NULL;
+                break;
+            } else {
+                arrayInit(part);
+            }
+        } else {
+            arrayPush(part) = c;
+        }
+    }
+    if (arrayLen(part) == 0) {
+        arrayRelease(part);
+    } else {
+        arrayPush(local_parts) = part;
+    }
+
+    arrayInit(part);
+    arrayPush(part) = '\0';
+    arrayPush(local_parts) = part;
+    p->argc = arrayLen(local_parts);
+    p->argv = local_parts;
+
+    return 0;
+}
+
+int parse_line(char const *const line, process **processes) {
+    //Splits the line at | and then parses the commands
+    int ret_code = 0;
+
+    if (arrayInit(*processes) != 0) {
+        perror("Failed to initialize processes array");
+        return -1;
+    }
+    bool done = false;
+    char const *cursor = line;
+    while (!done) {
+        process p = {.in_fd = 0, .out_fd = 0, .pid = 0, .blocking = true};
+        char const *end = strchr(cursor, '|');
+        if (end == NULL) {
+            done = true;
+            end = line + strlen(line);
+        }
+        if ((ret_code = parse_command(cursor, end, &p)) != 0) {
+            return ret_code;
+        }
+
+        arrayPush(*processes) = p;
+        cursor = end + 1;
+    }
+    size_t p_len = arrayLen(*processes);
+    process * last = *processes + (p_len -1);
+
+    // Linking up all processes as we currently only have pipes for multiple commands
+
+    for (size_t i = 0; i < p_len -1 ; ++i) {
+        int fds[2];
+        if(pipe(fds) != 0) {
+            perror("Failed to create pipe");
+            return -1;
+        }
+        (*processes)[i].out_fd=fds[1];
+        (*processes)[i+1].in_fd=fds[0];
+
+    }
+    // Setting all processes to non blocking when
+    if(strcmp(last->argv[last->argc-2], "&")== 0) {
+        arrayPop(last->argv);
+        last->argc = last->argc - 1;
+
+        for (size_t i = 0; i < p_len; ++i) {
+            (*processes)[i].blocking = false;
+        }
+    }
+    return ret_code;
+}
+
+int exec_command(process p, unsigned timeout) {
+    timeout = timeout ^ timeout;
+    int pid;
+    int status;
+
+    if ((pid = fork()) == 0) {
+        if (p.in_fd != 0) {
+            dup2(p.in_fd, 0);
+        }
+        if (p.out_fd != 0) {
+            dup2(p.out_fd, 1);
+        }
+        execvp(p.argv[0], p.argv);
+        fprintf(stderr, "could not execute \"%s\"\n", p.argv[0]);
+        fflush(stderr);
+        exit(-1);
+    }
+
+    if (pid < 0) {
+        fprintf(stderr, "no fork\n");
+        exit(-2);
+    }
+
+    waitpid(pid, &status, 0);
+
+    return WEXITSTATUS(status);
+}
+
+int free_processes(process ** pr) {
+    process *  processes = * pr;
+    while (!arrayIsEmpty(processes)) {
+        process p = arrayPop(processes);
+        while (!arrayIsEmpty(p.argv)) {
+            char *tmp = arrayPop(p.argv);
+            if (tmp)
+                arrayRelease(tmp);
+        }
+        arrayRelease(p.argv);
+    }
+    arrayRelease(processes);
+    *pr = NULL;
+}
\ No newline at end of file
-- 
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