diff options
Diffstat (limited to '02_exercise/process.c')
| -rw-r--r-- | 02_exercise/process.c | 148 |
1 files changed, 148 insertions, 0 deletions
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 |