refactor and add su

16 files changed, 168 insertions, 73 deletions

diff --git a/command/chmod.c b/command/chmod.c
index 9e2972e..ef4ec3d 100644
--- a/command/chmod.c
+++ b/command/chmod.c
@@ -1,4 +1,3 @@
-#include "args.h"
 #include "command.h"
 #include "lslib.h"
 
@@ -7,7 +6,6 @@
 #include <pwd.h>
 #include <unistd.h>
 #include <dirent.h>
-#include <errno.h>
 #include <string.h>
 
 enum method {
@@ -27,7 +25,7 @@ static struct {
 
 static void help (void) {
     printf("Usage: chmod [-Rcvf] MODE[,MODE]... FILE...\n\n");
-    printf("MODE is octal number (bit pattern sstrwxrwxrwx) or [ugoa]{+|-|=}[rwxXst]\n\n");
+    printf("MODE is octal number (bit pattern sstrwxrwxrwx) or {+|-|=}[rwxXst]\n\n");
     printf("\t-R\tRecurse\n");
 	printf("\t-c\tList changed files\n");
 	printf("\t-v\tVerbose\n");
@@ -73,7 +71,7 @@ static void chmod_file(char* path) {
     
     if (lstat(get_path_buffer(), &s) < 0) {
         if (!flags.quiet) {
-            error_s("cannot stat '%s': %s", get_path_buffer(), strerror(errno));
+            error_s("cannot stat '%s'", get_path_buffer());
         }
         pop_path_buffer(save);
         return;
@@ -89,7 +87,7 @@ static void chmod_file(char* path) {
     
     if (chmod(get_path_buffer(), mode) < 0) {
         if (!flags.quiet) {
-            error_s("cannot chmod '%s': %s", get_path_buffer(), strerror(errno));
+            error_s("cannot chmod '%s'", get_path_buffer());
         }
         pop_path_buffer(save);
         return;
@@ -110,7 +108,7 @@ static void chmod_file(char* path) {
     d = opendir(get_path_buffer());
     if (d == NULL) {
         if (!flags.quiet) {
-            error_s("cannot open dir '%s': %s", get_path_buffer(), strerror(errno));
+            error_s("cannot open dir '%s'", get_path_buffer());
         }
         pop_path_buffer(save);
         return;
diff --git a/command/chown.c b/command/chown.c
index 164e3b4..dcb6941 100644
--- a/command/chown.c
+++ b/command/chown.c
@@ -6,7 +6,6 @@
 #include <stdlib.h>
 #include <sys/stat.h>
 #include <unistd.h>
-#include <errno.h>
 #include <string.h>
 #include <sys/types.h>
 #include <pwd.h>
@@ -60,7 +59,7 @@ static void chown_file(char* path) {
     
     if (chown(get_path_buffer(), flags.uid, flags.gid) < 0) {
         if (!flags.quiet) {
-            error_s("cannot chown '%s': %s", get_path_buffer(), strerror(errno));
+            error_s("cannot chown '%s'", get_path_buffer());
         }
         pop_path_buffer(save);
         return;
@@ -75,7 +74,7 @@ static void chown_file(char* path) {
 
     if (lstat(get_path_buffer(), &s) < 0) {
         if (!flags.quiet) {
-            error_s("cannot stat '%s': %s", get_path_buffer(), strerror(errno));
+            error_s("cannot stat '%s'", get_path_buffer());
         }
         pop_path_buffer(save);
         return;
@@ -89,7 +88,7 @@ static void chown_file(char* path) {
     d = opendir(get_path_buffer());
     if (d == NULL) {
         if (!flags.quiet) {
-            error_s("cannot open dir '%s': %s", get_path_buffer(), strerror(errno));
+            error_s("cannot open dir '%s'", get_path_buffer());
         }
         pop_path_buffer(save);
         return;
diff --git a/command/cp.c b/command/cp.c
index ca80f69..47a4ff0 100644
--- a/command/cp.c
+++ b/command/cp.c
@@ -2,12 +2,12 @@
 #include "lslib.h"
 
 #include <dirent.h>
-#include <errno.h>
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
+#include <errno.h>
 #include <unistd.h>
 
 static struct {
@@ -81,7 +81,7 @@ static bool copy_file(char* from, char* to) {
 
 static bool symlink_file(char* from, char* to) {
     if (symlink(from, to) < 0) {
-        error_s("failed to symlink '%s': %s", from, strerror(errno));
+        error_s("failed to symlink '%s'", from);
         return false;
     } else if (flags.verbose) {
         output("symlinked '%s'", from);
@@ -91,7 +91,7 @@ static bool symlink_file(char* from, char* to) {
 
 static bool hardlink_file(char* from, char* to) {
     if (link(from, to) < 0) {
-        error_s("failed to hardlink '%s': %s", from, strerror(errno));
+        error_s("failed to hardlink '%s'", from);
         return false;
     } else if (flags.verbose) {
         output("hardlinked '%s'", from);
@@ -117,12 +117,12 @@ static void run_copy(struct stat* s) {
     if (!flags.preserve) return;
 
     if (chmod(to, s->st_mode) < 0) {
-        error_s("cannot chmod '%s': %s", to, strerror(errno));
+        error_s("cannot chmod '%s'", to);
         return;
     }
 
     if (chown(to, s->st_uid, s->st_gid) < 0) {
-        error_s("cannot chown '%s': %s", to, strerror(errno));
+        error_s("cannot chown '%s'", to);
         return;
     }
 }
@@ -140,14 +140,14 @@ static void cp_directory(struct stat* s) {
     }
 
     if (mkdir(get_path_buffer_2(), s->st_mode) < 0 && errno != EEXIST) {
-        error_s("cannot create directory '%s': %s", get_path_buffer_2(), strerror(errno));
+        error_s("cannot create directory '%s'", get_path_buffer_2());
         return;
     }
 
     d = opendir(get_path_buffer());
 
     if (d == NULL) {
-        error_s("cannot open directory '%s': %s", get_path_buffer(), strerror(errno));
+        error_s("cannot open directory '%s'", get_path_buffer());
         return;
     }
 
@@ -183,7 +183,7 @@ static void cp_file(char* path) {
     struct stat s;
     if (lstat(get_path_buffer(), &s) < 0) {
         pop_path_buffer(save);
-        error_s("cannot stat '%s': %s", get_path_buffer(), strerror(errno));
+        error_s("cannot stat '%s'", get_path_buffer());
         return;
     }
 
@@ -218,7 +218,7 @@ COMMAND(cp) {
     if (argc - start == 2) {
         struct stat s;
         if (lstat(argv[start], &s) < 0) {
-            error("cannot stat '%s': %s", argv[start], strerror(errno));
+            error("cannot stat '%s'", argv[start]);
         }
         push_path_buffer(argv[argc-2]);
         push_path_buffer_2(argv[argc-1]);
@@ -234,7 +234,7 @@ COMMAND(cp) {
     push_path_buffer_2(argv[argc-1]);
 
     if (lstat(get_path_buffer_2(), &s) < 0) {
-        error("target: '%s': %s", get_path_buffer_2(), strerror(errno));
+        error("target: '%s'", get_path_buffer_2());
     }
 
     for (i = start; i < argc - 1; i++) {
diff --git a/command/dd.c b/command/dd.c
index 67f8be3..1fb81c5 100644
--- a/command/dd.c
+++ b/command/dd.c
@@ -48,7 +48,7 @@ COMMAND(dd) {
         }
     }
  
-    buffer = malloc(bs);
+    buffer = xalloc(bs);
     
     while ((read = fread(buffer, 1, bs, in_file)) != 0) {
         fwrite(buffer, 1, read, out_file);
diff --git a/command/ed.c b/command/ed.c
index 472473f..8e8eae1 100644
--- a/command/ed.c
+++ b/command/ed.c
@@ -76,7 +76,7 @@ static bool parse_regex(char** end, struct LineAddress* address, enum RegexDirec
 
     cap = 8;
     siz = 0;
-    buf = malloc(cap * sizeof(long int));
+    buf = xalloc(cap * sizeof(long int));
 
     i = (dir == ALL ? 0 : line_current);
     until = (dir == BEFORE ? 0 : line_count - 1);
@@ -88,7 +88,7 @@ static bool parse_regex(char** end, struct LineAddress* address, enum RegexDirec
         }
         if (cap == siz) {
             cap *= 2;
-            buf = realloc(buf, cap * sizeof(long int));
+            buf = xrealloc(buf, cap * sizeof(long int));
         }
         buf[siz] = i;
         siz++;
@@ -112,7 +112,7 @@ static void free_address (struct LineAddress address) {
 static void expand_buffer(long int** buf, unsigned long* cap, unsigned long* size) {
     if (*cap == *size) {
         *cap *= 2;
-        *buf = realloc(*buf, sizeof(long int) * *cap);
+        *buf = xrealloc(*buf, sizeof(long int) * *cap);
     }
 }
 
@@ -127,7 +127,7 @@ static bool parse_regex_lines(char** end, struct LineAddress* address) {
 
     cap = 8;
     siz = 0;
-    buf = malloc(cap * sizeof(long int));
+    buf = xalloc(cap * sizeof(long int));
 
     addr = *address;
     if (addr.type == INDEX) {
@@ -310,7 +310,7 @@ static void load_empty(void) {
     free_data(false);
 
     line_capacity = 8;
-    lines = malloc(sizeof(char*) * line_capacity);
+    lines = xalloc(sizeof(char*) * line_capacity);
 
     line_count = 0;
     line_current = 0;
@@ -320,7 +320,7 @@ static void load_empty(void) {
 static void get_input(FILE* file, char*** buffer, unsigned long* capacity, unsigned long* size) {
     unsigned long cap = 8;
     unsigned long siz = 0;
-    char** buf = malloc(sizeof(char*) * cap);
+    char** buf = xalloc(sizeof(char*) * cap);
 
     char* line = NULL;
     size_t offset = 0;
@@ -329,7 +329,7 @@ static void get_input(FILE* file, char*** buffer, unsigned long* capacity, unsig
     while (getline(&line, &offset, file) != -1) {
         if (cap == siz) {
             cap *= 2;
-            buf = realloc(buf, sizeof(char*) * cap);
+            buf = xrealloc(buf, sizeof(char*) * cap);
         }
         buf[siz] = line;
         siz++;
@@ -400,7 +400,7 @@ static void expand(unsigned long count) {
     if (count < line_capacity) return;
     line_capacity *= 2;
     if (count > line_capacity) line_capacity = count;
-    lines = realloc(lines, line_capacity * sizeof(char*));
+    lines = xrealloc(lines, line_capacity * sizeof(char*));
 }
 
 static void append_lines(unsigned long index, char** new, unsigned long new_len) {
@@ -495,9 +495,9 @@ static bool get_file_name(char** filename) {
             len--;
         }
         if (default_filename != NULL) {
-            default_filename = realloc(default_filename, len + 1);
+            default_filename = xrealloc(default_filename, len + 1);
         } else {
-            default_filename = malloc(len + 1);
+            default_filename = xalloc(len + 1);
         }
         memcpy(default_filename, *filename, len + 1);
         *filename = default_filename;
@@ -561,7 +561,7 @@ static void read_file(char* filename) {
 
     capacity = 8;
     size = 0;
-    buf = malloc(capacity * sizeof(char*));
+    buf = xalloc(capacity * sizeof(char*));
     get_input(file, &buf, &capacity, &size);
 
     if (size < 1) {
@@ -584,7 +584,7 @@ static void expand_string(char** buf, int* capacity, int* size, char* text, int
     if (*size + len >= *capacity) {
         *capacity *= 2;
         if (*capacity < *size + len) *capacity = *size + len;
-        *buf = realloc(*buf, *capacity);
+        *buf = xrealloc(*buf, *capacity);
     }
     memcpy(*buf + *size, text, len);
     *size += len;
@@ -593,7 +593,7 @@ static void expand_string(char** buf, int* capacity, int* size, char* text, int
 static int substute_string(long int index, long int matches, re_t regex, char* sub, int sub_len) {
     int capacity = 8;
     int size = 0;
-    char* buf = malloc(sizeof(char) * capacity);
+    char* buf = xalloc(sizeof(char) * capacity);
     long int left;
 
     int offset = 0;
diff --git a/command/groups.c b/command/groups.c
index cb950be..f95ee80 100644
--- a/command/groups.c
+++ b/command/groups.c
@@ -1,13 +1,12 @@
-#include "args.h"
 #include "command.h"
 #include "lslib.h"
 
-#include <errno.h>
 #include <grp.h>
 #include <pwd.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <errno.h>
 
 static void help (void) {
     printf("Usage: groups [USER]\n\n");
@@ -34,14 +33,14 @@ COMMAND(groups) {
         if (errno == 0) {
             error("user not found");
         } else {
-            error("failed to fetch groups: %s", strerror(errno));
+            error("failed to fetch groups");
         }
     }
     
     ngroups = 0;
     getgrouplist(pw->pw_name, pw->pw_gid, NULL, &ngroups);
     
-    groups = malloc(sizeof(gid_t) * ngroups);
+    groups = xalloc(sizeof(gid_t) * ngroups);
     getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups);
    
     for (i = 0; i < ngroups; i++){
@@ -49,7 +48,7 @@ COMMAND(groups) {
 
         if(gr == NULL) {
             free(groups);
-            error("failed to fetch groups: %s", strerror(errno));
+            error("failed to fetch groups");
         }
 
         printf("%s ",gr->gr_name);
diff --git a/command/id.c b/command/id.c
index 3a63989..3d3d19e 100644
--- a/command/id.c
+++ b/command/id.c
@@ -1,13 +1,12 @@
-#include "args.h"
 #include "command.h"
 #include "lslib.h"
 
-#include <errno.h>
 #include <grp.h>
 #include <pwd.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <errno.h>
 
 static void help (void) {
     printf("Usage: id [USER]\n\n");
@@ -35,7 +34,7 @@ COMMAND(user_id) {
         if (errno == 0) {
             error("user not found");
         } else {
-            error("failed to fetch groups: %s", strerror(errno));
+            error("failed to fetch groups");
         }
     }
 
@@ -44,7 +43,7 @@ COMMAND(user_id) {
     ngroups = 0;
     getgrouplist(pw->pw_name, pw->pw_gid, NULL, &ngroups);
     
-    groups = malloc(sizeof(gid_t) * ngroups);
+    groups = xalloc(sizeof(gid_t) * ngroups);
     getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups);
    
     gid = pw->pw_gid;
@@ -60,7 +59,7 @@ COMMAND(user_id) {
         struct group* gr = getgrgid(groups[i]);
         if(gr == NULL) {
             free(groups);
-            error("failed to fetch groups: %s", strerror(errno));
+            error("failed to fetch groups");
         }
         
         printf("%d(%s)", gr->gr_gid, gr->gr_name);
diff --git a/command/ls.c b/command/ls.c
index bbfedfb..d4d19c1 100644
--- a/command/ls.c
+++ b/command/ls.c
@@ -66,9 +66,9 @@ static DIR* get_directory(char* path) {
     DIR* d = opendir(path);
     if (d == NULL) {
         if (errno == ENOTDIR) {
-            error_s("`%s` is a a file\n", path);
+            error_s("`%s` is a a file", path);
         } else {
-            error_s("failed to open directory '%s': %s\n", path, strerror(errno));
+            error_s("failed to open directory '%s'", path);
         }
     }
     return d;
@@ -90,7 +90,7 @@ static bool get_file_info(const char* file_name, struct FileInfo* info) {
     save = push_path_buffer(file_name);
 
     if (lstat(get_path_buffer(), &s) < 0) {
-        error_s("failed to read file '%s': %s\n", get_path_buffer(), strerror(errno));
+        error_s("failed to read file '%s'", get_path_buffer());
         pop_path_buffer(save);
         return false;
     }
@@ -199,7 +199,7 @@ static bool get_file_info(const char* file_name, struct FileInfo* info) {
     info->type = ty;
 
     file_len = strlen(file_name) + 1;
-    info->name = malloc(file_len);
+    info->name = xalloc(file_len);
     memcpy(info->name, file_name, file_len);
 
     print_file_size(s.st_size, info->size);
@@ -340,7 +340,7 @@ static void push_file(
 
     if (*size == *capacity) {
         *capacity *= 2;
-        *files = realloc(*files, sizeof(struct FileInfo) * *capacity);
+        *files = xrealloc(*files, sizeof(struct FileInfo) * *capacity);
     }
     
     user_len = strlen(finfo.usr->pw_name);
@@ -382,7 +382,7 @@ static void recurse_directory(char* dir_name) {
     capacity = 8;
     size = 0;
     
-    files = malloc(sizeof(struct FileInfo) * capacity);
+    files = xalloc(sizeof(struct FileInfo) * capacity);
     memset(&info, 0, sizeof(struct FileListInfo));
 
     while((file = readdir(d)) != NULL) {
@@ -434,7 +434,7 @@ static void list_directory(char* path) {
     capacity = 8;
     size = 0;
     
-    files = malloc(sizeof(struct FileInfo) * capacity);
+    files = xalloc(sizeof(struct FileInfo) * capacity);
     memset(&info, 0, sizeof(struct FileListInfo));
     
     while ((file = readdir(d)) != NULL) {
@@ -466,7 +466,7 @@ static void list_file_args(int start, int argc, char** argv) {
     capacity = 8;
     size = 0;
     
-    files = malloc(sizeof(struct FileInfo) * capacity);
+    files = xalloc(sizeof(struct FileInfo) * capacity);
     memset(&info, 0, sizeof(struct FileListInfo));
     
     for (i = start; i < argc; i++) {
diff --git a/command/mkdir.c b/command/mkdir.c
index 0d3950d..e6d6268 100644
--- a/command/mkdir.c
+++ b/command/mkdir.c
@@ -38,7 +38,7 @@ static bool mkdir_parents(char* path) {
         if (path[i] != '/') continue;
         path[i] = '\0';
         if (mkdir(path, flags.mode) < 0 && errno != EEXIST) {
-            error_s("failed to create directory '%s': %s", path, strerror(errno));
+            error_s("failed to create directory '%s'", path);
             return false;
         };
         path[i] = '/';
@@ -62,7 +62,7 @@ COMMAND(makedir) {
             continue;
         }
         if (mkdir(argv[i], flags.mode) < 0) {
-            error_s("failed to create directory '%s': %s", argv[i], strerror(errno));
+            error_s("failed to create directory '%s'", argv[i]);
         }
     }
 
diff --git a/command/mv.c b/command/mv.c
index adce2b7..8f8f0c7 100644
--- a/command/mv.c
+++ b/command/mv.c
@@ -64,7 +64,7 @@ static void mv_dir(bool exists) {
     }
     
     if (rename(get_path_buffer(), get_path_buffer_2()) < 0) {
-        error_s("cannot move '%s': %s", get_path_buffer(), strerror(errno));
+        error_s("cannot move '%s'", get_path_buffer());
     } else if (flags.verbose) {
         output("moved '%s'", get_path_buffer());
     }
@@ -91,7 +91,7 @@ COMMAND(mv) {
     dest = true;
     if (lstat(get_path_buffer_2(), &s) < 0 && argc - start > 2) {
         dest = false;
-        error("cannot stat '%s': %s", get_path_buffer_2(), strerror(errno));
+        error("cannot stat '%s'", get_path_buffer_2());
     }
     
     if (dest && flags.refuse_if_dir) {
diff --git a/command/rm.c b/command/rm.c
index 81a956a..9834a40 100644
--- a/command/rm.c
+++ b/command/rm.c
@@ -52,7 +52,7 @@ static bool rm_dir (void) {
     
     d = opendir(get_path_buffer());
     if (d == NULL) {
-        error_s("failed to stat '%s': %s\n", get_path_buffer(), strerror(errno));
+        error_s("failed to stat '%s'", get_path_buffer());
         return false;
     }
 
@@ -71,7 +71,7 @@ static void rm_file(char* path) {
     struct stat s;
     if (lstat(get_path_buffer(), &s) < 0) {
         pop_path_buffer(save);
-        error_s("failed to stat '%s': %s\n", get_path_buffer(), strerror(errno));
+        error_s("failed to stat '%s'", get_path_buffer());
         return;
     }
 
@@ -102,7 +102,7 @@ static void rm_file(char* path) {
     }
 
     if (remove(get_path_buffer()) < 0) {
-        error_s("failed to delete '%s': %s\n", get_path_buffer(), strerror(errno));
+        error_s("failed to delete '%s'", get_path_buffer());
     } else if (flags.verbose) {
         output("deleted '%s'\n", get_path_buffer());
     }
diff --git a/command/su.c b/command/su.c
new file mode 100644
index 0000000..942f37e
--- /dev/null
+++ b/command/su.c
@@ -0,0 +1,104 @@
+#include "command.h"
+#include "lslib.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static struct {
+    bool clear_env;
+    bool update_env;
+    char* shell;
+    char* user;
+} flags;
+
+static bool restricted_shell(const char *shell) {
+	char *line;
+	int result = true;
+
+	while ((line = getusershell()) != NULL) {
+		if (strcmp(line, shell) == 0) {
+			result = false;
+			break;
+		}
+	}
+	endusershell();
+	return result;
+}
+
+static void help (void) {
+    printf("Usage: su [-lmp] [-s SH] [-] [USER [FILE ARGS]] \n\n");
+    printf("Run shell under USER (by default, root)\n\n");
+	printf("\t-,-l\tClear environment, go to home dir, run shell as login shell\n");
+	printf("\t-p,-m\tDo not set new $HOME, $SHELL, $USER, $LOGNAME\n");
+	printf("\t-s SH	Shell\tto use instead of user's default\n");
+}
+
+static int short_arg (char c, char* next) {
+    switch (c) {
+        case 'l':
+            flags.clear_env = true;
+            break;
+        case 'p':
+        case 'm':
+            flags.update_env = false;
+            break;
+        case 's':
+            check_arg(next);
+            flags.shell = next;
+            return ARG_USED;
+        default:
+            return ARG_INVALID;
+    
+    }
+    return ARG_UNUSED;
+}
+
+COMMAND (su) {
+     
+    int start, res;
+    uid_t cur_uid;
+    struct passwd* pw;
+
+    flags.clear_env = false;
+    flags.update_env = true;
+    flags.shell = NULL;
+    flags.user = "root";
+
+    start = parse_args(argc, argv, help, short_arg, NULL);
+
+    if (start < argc && streql(argv[start], "-")) {
+        flags.clear_env = true;
+        start++;
+    }
+
+    if (start < argc)
+        flags.user = argv[start++];
+
+    pw = xgetpwnam(flags.user);
+    cur_uid = getuid();
+
+    if (cur_uid != 0) {
+        res = prompt_password(pw, "Password: ");
+    } else {
+        res = PASSWORD_VALID;
+    }
+
+    if (res != PASSWORD_VALID) {
+        error("invalid password");
+    }
+
+    if (flags.shell && cur_uid != 0 && pw->pw_shell && restricted_shell(pw->pw_shell)) {
+        error_s("using restricted shell");
+        flags.shell = NULL;
+    }
+
+    if (!flags.shell)
+        flags.shell = pw->pw_shell;
+
+    change_identity(pw);
+    setup_environment(flags.shell, flags.update_env, flags.clear_env, pw);
+    exec_shell(flags.shell, flags.clear_env, (const char**) &argv[start]);
+
+    return EXIT_FAILURE; /* */
+}
diff --git a/command/sync.c b/command/sync.c
index 797d7a5..89ff86f 100644
--- a/command/sync.c
+++ b/command/sync.c
@@ -1,12 +1,9 @@
-#include "args.h"
 #include "command.h"
 #include "lslib.h"
 
-#define _X_OPEN_SOURCE 500
 #include <stdlib.h>
 #include <unistd.h>
 #include <fcntl.h>
-#include <errno.h>
 #include <string.h>
 
 static struct {
@@ -58,7 +55,7 @@ static bool sync_file(char* path) {
     } else {
         ret = flags.sync_data ? fdatasync(fd) : fsync(fd);
         if (ret < 0) {
-            error_s("failed to sync '%s': %s", path, strerror(errno));
+            error_s("failed to sync '%s'", path);
         }
     }
 
diff --git a/command/tail.c b/command/tail.c
index 8137eca..64f4608 100644
--- a/command/tail.c
+++ b/command/tail.c
@@ -23,10 +23,10 @@ static size_t tail_file_lines(FILE* file, unsigned int count, size_t skip) {
     size_t len;
     char* line;
 
-    ring = malloc(sizeof(char*) * count);
+    ring = xalloc(sizeof(char*) * count);
     memset(ring, 0, sizeof(char*) * count);
 
-    ring_len = malloc(sizeof(int) * count);
+    ring_len = xalloc(sizeof(int) * count);
     
     index = 0;
     size = 0;
@@ -74,7 +74,7 @@ static size_t tail_file_chars(FILE* file, unsigned int count, size_t skip) {
     unsigned int size, i;
     int read, c;
 
-    ring = malloc(sizeof(char) * count);
+    ring = xalloc(sizeof(char) * count);
     memset(ring, 0, count);
 
     index = 0;
diff --git a/command/tee.c b/command/tee.c
index 364a13d..b9ff974 100644
--- a/command/tee.c
+++ b/command/tee.c
@@ -71,7 +71,7 @@ COMMAND(tee_cmd) {
         return EXIT_SUCCESS;
     }
 
-    files = malloc(sizeof(FILE*) * (argc - start));
+    files = xalloc(sizeof(FILE*) * (argc - start));
 
     for (i = start; i < argc; i++) {
         FILE* file = get_file(argv[i], flags.append ? "a" : "w");
diff --git a/command/xargs.c b/command/xargs.c
index 2a41460..47e0f0b 100644
--- a/command/xargs.c
+++ b/command/xargs.c
@@ -1,7 +1,6 @@
 #include "command.h"
 #include "lslib.h"
 
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -76,7 +75,7 @@ char* read_next(FILE* file, int arg_count) {
 
     size = 0;
     capacity = 8;
-    buf = malloc(sizeof(char) * capacity);
+    buf = xalloc(sizeof(char) * capacity);
 
     while(c = getc(file), true) {
         if (c == EOF && size == 0) {
@@ -86,7 +85,7 @@ char* read_next(FILE* file, int arg_count) {
 
         if (size == capacity) {
             capacity *= 2;
-            buf = realloc(buf, sizeof(char) * capacity);
+            buf = xrealloc(buf, sizeof(char) * capacity);
         }
 
         if (c == '\0' || c == EOF || (!flags.null_seperated && c == '\n')) {
@@ -104,7 +103,7 @@ void read_args(FILE* file, char*** args, int* size, int* capacity) {
     while (arg = read_next(file, read), true) {
         if (*size == *capacity) {
             *capacity *= 2;
-            *args = realloc(*args, sizeof(char*) * *capacity);
+            *args = xrealloc(*args, sizeof(char*) * *capacity);
         }
         (*args)[(*size)++] = arg;
         read++;
@@ -146,7 +145,7 @@ COMMAND(xargs) {
     size = arg_on_stack_count + 1;
     capacity = size + 8;
     
-    args = malloc(sizeof(char*) * capacity);
+    args = xalloc(sizeof(char*) * capacity);
     args[0] = command;
     memcpy(&args[1], &argv[arg_start], arg_on_stack_count * sizeof(char*));
     read_args(flags.file, &args, &size, &capacity);
@@ -178,7 +177,7 @@ COMMAND(xargs) {
     }
 
     if (execvp(command, args) == -1) {
-        error("error: failed to execute command: %s", strerror(errno));
+        error("failed to execute command");
     }
 
 cleanup: