feat[OS/lab5]: completed part B

OSs/lab5/part-B/Makefile

@@ -0,0 +1,15 @@
+targets = server client
+all: $(targets)
+
+server: server.o
+	$(CC) -o $@ $^ $(CFLAGS)
+
+client: client.o
+	$(CC) -o $@ $^ $(CFLAGS)
+
+%.o: %.c
+	$(CC) -c $^ -o $@ $(CFLAGS)
+
+clean:
+	rm -f $(targets)
+	rm -f *.o

OSs/lab5/part-B/client.c

@@ -0,0 +1,80 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <ctype.h>
+#include <fcntl.h>
+
+#include "common.h"
+
+int client(int fd_read, int fd_write);
+
+int main()
+{
+    int read_fd, write_fd;
+    FAIL_ON((write_fd=open(FIFO_SERVER_PATH, O_WRONLY)) < 0);
+    FAIL_ON((read_fd=open(FIFO_CLIENT_PATH, O_RDONLY)) < 0);
+
+    FAIL_ON(client(read_fd, write_fd));
+
+    FAIL_ON(unlink(FIFO_SERVER_PATH) < 0);
+    printf("unlinked %s\n", FIFO_SERVER_PATH);
+    FAIL_ON(unlink(FIFO_CLIENT_PATH) < 0);
+    printf("unlinked %s\n", FIFO_CLIENT_PATH);
+
+    return EXIT_SUCCESS;
+}
+
+#define BUF_SIZE 256
+
+char *ltrim(char *s)
+{
+    while(isspace(*s)) s++;
+    return s;
+}
+
+char *rtrim(char *s)
+{
+    char* back = s + strlen(s);
+    while(isspace(*--back));
+    *(back+1) = '\0';
+    return s;
+}
+
+char *trim(char *s)
+{
+    return rtrim(ltrim(s)); 
+}
+
+/**
+ * Performs client actions
+ *
+ * @fd_read - pipe to read from
+ * @fd_write - pipe to write t\no
+ * 
+ * returns 0 on success or -errno on fail
+ */
+int client(int fd_read, int fd_write)
+{
+    char buf[BUF_SIZE] = {0};
+    if (!fgets(buf, BUF_SIZE, stdin)) return -EFAULT;
+    const char *s = trim(buf);
+    size_t len = strlen(s);
+    ssize_t n_written = write(fd_write, s, len);
+    if (n_written < 0 || n_written < len) {
+        return -EFAULT;
+    }
+    memset(buf, 0, BUF_SIZE);
+    size_t n;
+    struct custom_ds ds;
+    while ((n = recv_msg(fd_read, &ds)) > 0) {
+        len = ds.hdr.len;
+        n_written = fwrite(ds.msg, sizeof(ds.msg[0]), len, stdout);
+        if (n_written < 0 || n_written < len) {
+            return -EFAULT;
+        }
+        memset(buf, 0, sizeof(buf));
+    }
+    return 0;
+}

OSs/lab5/part-B/common.h

@@ -0,0 +1,45 @@
+#ifndef COMMON_H_
+#define COMMON_H_
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+#define FIFO_SERVER_PATH "/tmp/fifo.to_server" // server reads this file
+#define FIFO_CLIENT_PATH "/tmp/fifo.to_client" // client reads this file
+
+#define __DATA_STRUCT_MSG_LEN 4096
+
+enum ds_types {
+    DS_MESSAGE,
+    DS_FAIL
+};
+
+struct custom_ds {
+    struct {
+        long len;
+        long type;
+    } hdr;
+    char msg[__DATA_STRUCT_MSG_LEN];
+};
+
+static inline ssize_t send_msg(int fd, const struct custom_ds *ds)
+{
+    return write(fd, ds, sizeof(ds->hdr) + ds->hdr.len);
+}
+
+static inline ssize_t recv_msg(int fd, struct custom_ds *reciever)
+{
+    size_t n_hdr = read(fd, reciever, sizeof(reciever->hdr));
+    if (n_hdr == 0) return 0; // eof reached
+    if (n_hdr != sizeof(reciever->hdr)) return -ENOMSG;
+    if (reciever->hdr.len == 0) return 0;
+
+    size_t n_payload = read(fd, &reciever->msg, reciever->hdr.len);
+    if (n_payload != reciever->hdr.len) return -EFAULT;
+    return n_hdr + n_payload;
+}
+
+#define FAIL_ON(cond) if (cond) return EXIT_FAILURE
+
+#endif

OSs/lab5/part-B/server.c

@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "common.h"
+
+int server(int fd_read, int fd_write);
+
+int main()
+{
+    FAIL_ON(mknod(FIFO_SERVER_PATH, S_IFIFO | 0666, 0) < 0);
+    printf("created %s\n", FIFO_SERVER_PATH);
+    FAIL_ON(mknod(FIFO_CLIENT_PATH, S_IFIFO | 0666, 0) < 0);
+    printf("created %s\n", FIFO_CLIENT_PATH);
+
+    int read_fd, write_fd;
+    FAIL_ON((read_fd=open(FIFO_SERVER_PATH, O_RDONLY)) < 0);
+    FAIL_ON((write_fd=open(FIFO_CLIENT_PATH, O_WRONLY)) < 0);
+
+    return server(read_fd, write_fd);
+}
+
+#define BUF_SIZE 256
+
+/**
+ * Performs server actions
+ *
+ * @fd_read - pipe to read from
+ * @fd_write - pipe to write to
+ *
+ * returns 0 on success or -errno on fail
+ */
+int server(int fd_read, int fd_write)
+{
+    char buf[BUF_SIZE] = {0};
+    size_t n = read(fd_read, buf, BUF_SIZE);
+    if (n == 0) return -EFAULT;
+    FILE *f = fopen(buf, "r");
+    // не 100% правильно, но наиболее вероятно
+    if (f == NULL) {
+        const char error_msg[] = "Can't open requested file\n";
+        struct custom_ds payload = {
+            .hdr.len = sizeof(error_msg),
+            .hdr.type = DS_FAIL,
+        };
+        strncpy(payload.msg, error_msg, sizeof(error_msg));
+        send_msg(fd_write, &payload);
+        goto epilog;
+    }
+
+    while ((n = fread(buf, sizeof(buf[0]), BUF_SIZE, f)) > 0) {
+        struct custom_ds payload = {
+            .hdr.len = n,
+            .hdr.type = DS_MESSAGE,
+        };
+        strncpy(payload.msg, buf, n);
+        send_msg(fd_write, &payload);
+        memset(buf, 0, sizeof(buf));
+    }
+
+epilog:
+    fclose(f);
+    return 0;
+}