Update MentOs code to the latest development version.

libc/src/grp.c

@@ -0,0 +1,238 @@
+///                MentOS, The Mentoring Operating system project
+/// @file grp.c
+/// @brief
+/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
+/// See LICENSE.md for details.
+
+#include "grp.h"  
+#include "sys/unistd.h"
+#include "sys/errno.h"
+#include "assert.h"
+#include "string.h"
+#include "stdio.h"
+#include "debug.h"
+#include "fcntl.h"
+
+
+static inline void __parse_line(struct group* grp, char *buf)
+{
+    assert(grp && "Received null grp!");
+    char *token;
+    // Parse the group name.
+    if ((token = strtok(buf, ":")) != NULL)
+        grp->gr_name = token;
+    // Parse the group passwd.
+    if ((token = strtok(NULL, ":")) != NULL)
+        grp->gr_passwd = token;
+    // Parse the group id.
+    if ((token = strtok(NULL, ":")) != NULL)
+        grp->gr_gid = atoi(token);
+
+    size_t found_users = 0;
+    while((token = strtok(NULL, ",\n\0")) != NULL && found_users < MAX_MEMBERS_PER_GROUP) {
+        grp->gr_mem[found_users] = token;
+        found_users += 1;
+    }
+
+    // Null terminate array
+    grp->gr_mem[found_users] = "\0";
+}
+
+static inline char *__search_entry(int fd, char *buf, int buflen, const char *name, gid_t gid)
+{
+    int ret;
+    char c;
+    int pos = 0;
+    while ((ret = read(fd, &c, 1U))) {
+        // Skip carriage return.
+        if (c == '\r')
+            continue;
+        if (pos >= buflen) {
+            errno = ERANGE;
+            return NULL;
+        }
+        // If we have found a newline or the EOF, parse the entry.
+        if ((c == '\n') || (ret == EOF)) {
+            // Close the buffer.
+            buf[pos] = 0;
+            // Check the entry.
+            if (name) {
+                if (strncmp(buf, name, strlen(name)) == 0)
+                    return buf;
+            } else {
+                int gid_start = -1, col_count = 0;
+                for (int i = 0; i < pos; ++i) {
+                    if (buf[i] == ':') {
+                        if (++col_count == 2) {
+                            gid_start = i + 1;
+                            break;
+                        }
+                    }
+                }
+                if ((gid_start != -1) && (gid_start < pos)) {
+                    // Parse the gid.
+                    int found_gid = atoi(&buf[gid_start]);
+                    // Check the gid.
+                    if (found_gid == gid)
+                        return buf;
+                }
+            }
+            // Reset the index.
+            pos = 0;
+            // If we have reached the EOF stop.
+            if (ret == EOF)
+                break;
+        } else {
+            buf[pos++] = c;
+        }
+    }
+    errno = ENOENT;
+    return NULL;
+}
+
+struct group* getgrgid(gid_t gid) {
+
+    static group grp;
+    static char buffer[BUFSIZ];
+
+    group *result;
+    if (!getgrgid_r(gid, &grp, buffer, BUFSIZ, &result))
+        return NULL;
+
+    return &grp;
+}
+
+struct group *getgrnam(const char* name) {
+    
+    if (name == NULL)
+        return NULL;
+
+    static group grp;
+    static char buffer[BUFSIZ];
+
+    group *result;
+    if (!getgrnam_r(name, &grp, buffer, BUFSIZ, &result))
+        return NULL;
+
+    return &grp;
+}
+
+int getgrgid_r(gid_t gid, struct group* group, char* buf, size_t buflen, struct group ** result) {
+    
+    int fd = open("/etc/group", O_RDONLY, 0);
+    if (fd == -1) {
+        errno   = ENOENT;
+        *result = NULL;
+        return 0;
+    }
+    
+    char *entry = __search_entry(fd, buf, buflen, NULL, gid);
+    if (entry != NULL) {
+
+        // Close the file.
+        close(fd);
+        // Parse the line.
+        __parse_line(group, entry);
+        // Return success.
+        return 1;
+    }
+
+    // Close the file.
+    close(fd);
+    // Return fail.
+    return 0;
+}
+
+int getgrnam_r(const char* name, struct group* group, char* buf, size_t buflen, struct group** result) {
+
+    int fd = open("/etc/group", O_RDONLY, 0);
+    if (fd == -1) {
+        errno   = ENOENT;
+        *result = NULL;
+        return 0;
+    }
+    
+    char *entry = __search_entry(fd, buf, buflen, name, 0);
+    if (entry != NULL) {
+
+        // Close the file.
+        close(fd);
+        // Parse the line.
+        __parse_line(group, entry);
+        // Return success.
+        return 1;
+    }
+
+    // Close the file.
+    close(fd);
+    // Return fail.
+    return 0;
+}
+
+static int fd = -1;
+struct group* getgrent(void) {
+
+    static group result;
+
+    if (fd == -1) {
+        //pr_debug("Opening group file\n");
+        fd = open("/etc/group", O_RDONLY, 0);
+        if (fd == -1) {
+            errno = ENOENT;
+            return 0;
+        }
+    }
+
+    int ret;
+    char c;
+    int pos = 0;
+
+    static char buffer[BUFSIZ];
+    while ((ret = read(fd, &c, 1U))) {
+
+        // Skip carriage return.
+        if (c == '\r')
+            continue;
+
+        if (pos >= BUFSIZ) {
+            errno = ERANGE;
+            return NULL;
+        }
+
+        // If we have found a newline or the EOF, parse the entry.
+        if ((c == '\n') || (ret == EOF)) {
+            // Close the buffer.
+            buffer[pos] = 0;
+
+            // Check the entry.
+            if (strlen(buffer) != 0) {
+                //pr_debug("Found entry in group file: %s\n", buffer);
+                __parse_line(&result, buffer);
+                return &result;
+            }
+
+            // If we have reached the EOF stop.
+            if (ret == EOF)
+                break;
+
+        } else {
+            buffer[pos++] = c;
+        }
+    }
+
+    errno = ENOENT;
+    return NULL;
+}
+
+void endgrent(void) {
+
+    //pr_debug("Closing group file\n");
+    close(fd);
+    fd = -1;
+}
+
+void setgrent(void) {
+
+    //pr_debug("Resetting pointer to beginning of group file\n");
+    lseek(fd, 0, SEEK_SET);
+}