ls: make readlink error to not disrupt output (try ls -l /proc/self/fd).

libbb: make xmalloc_readlink_or_warn warning more specific.

function                                             old     new   delta
xmalloc_readlink_or_warn                              33      61     +28
showfiles                                           1495    1460     -35
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 28/-35)             Total: -7 bytes

2 files changed, 102 insertions, 102 deletions

diff --git a/coreutils/ls.c b/coreutils/ls.c
index 8007f2a2e..85c6729ea 100644
--- a/coreutils/ls.c
+++ b/coreutils/ls.c
@@ -76,7 +76,7 @@ LIST_ID_NAME    = 1 << 4,
 LIST_ID_NUMERIC = 1 << 5,
 LIST_CONTEXT    = 1 << 6,
 LIST_SIZE       = 1 << 7,
-LIST_DEV        = 1 << 8,
+//LIST_DEV        = 1 << 8, - unused, synonym to LIST_SIZE
 LIST_DATE_TIME  = 1 << 9,
 LIST_FULLTIME   = 1 << 10,
 LIST_FILENAME   = 1 << 11,
@@ -741,8 +741,8 @@ static int print_name(const char *name)
 
 static int list_single(const struct dnode *dn)
 {
-        int i, column = 0;
-
+        int column = 0;
+        char *lpath;
 #if ENABLE_FEATURE_LS_TIMESTAMPS
         char *filetime;
         time_t ttime, age;
@@ -767,127 +767,123 @@ static int list_single(const struct dnode *dn)
         append = append_char(dn->dstat.st_mode);
 #endif
 
-        for (i = 0; i <= 31; i++) {
-                switch (all_fmt & (1 << i)) {
-                case LIST_INO:
-                        column += printf("%7lu ", (long) dn->dstat.st_ino);
-                        break;
-                case LIST_BLOCKS:
-                        column += printf("%4"OFF_FMT"u ", (off_t) dn->dstat.st_blocks >> 1);
-                        break;
-                case LIST_MODEBITS:
-                        column += printf("%-10s ", (char *) bb_mode_string(dn->dstat.st_mode));
-                        break;
-                case LIST_NLINKS:
-                        column += printf("%4lu ", (long) dn->dstat.st_nlink);
-                        break;
-                case LIST_ID_NAME:
+        /* Do readlink early, so that if it fails, error message
+         * does not appear *inside* of the "ls -l" line */
+        if (all_fmt & LIST_SYMLINK)
+                if (S_ISLNK(dn->dstat.st_mode))
+                        lpath = xmalloc_readlink_or_warn(dn->fullname);
+
+        if (all_fmt & LIST_INO)
+                column += printf("%7lu ", (long) dn->dstat.st_ino);
+        if (all_fmt & LIST_BLOCKS)
+                column += printf("%4"OFF_FMT"u ", (off_t) dn->dstat.st_blocks >> 1);
+        if (all_fmt & LIST_MODEBITS)
+                column += printf("%-10s ", (char *) bb_mode_string(dn->dstat.st_mode));
+        if (all_fmt & LIST_NLINKS)
+                column += printf("%4lu ", (long) dn->dstat.st_nlink);
 #if ENABLE_FEATURE_LS_USERNAME
-                        if (option_mask32 & OPT_g) {
-                                printf("%-8.8s",
-                                        get_cached_username(dn->dstat.st_uid));
-                                column += 9;
-                                break;
-                        }
-                        printf("%-8.8s %-8.8s",
+        if (all_fmt & LIST_ID_NAME) {
+                if (option_mask32 & OPT_g) {
+                        column += printf("%-8.8s",
+                                get_cached_username(dn->dstat.st_uid));
+                } else {
+                        column += printf("%-8.8s %-8.8s",
                                 get_cached_username(dn->dstat.st_uid),
                                 get_cached_groupname(dn->dstat.st_gid));
-                        column += 17;
-                        break;
+                }
+        }
 #endif
-                case LIST_ID_NUMERIC:
-                        column += printf("%-8u %-8u", dn->dstat.st_uid, dn->dstat.st_gid);
-                        break;
-                case LIST_SIZE:
-                case LIST_DEV:
-                        if (S_ISBLK(dn->dstat.st_mode) || S_ISCHR(dn->dstat.st_mode)) {
-                                column += printf("%4u, %3u ", (int) major(dn->dstat.st_rdev),
-                                           (int) minor(dn->dstat.st_rdev));
+        if (all_fmt & LIST_ID_NUMERIC) {
+                if (option_mask32 & OPT_g)
+                        column += printf("%-8u", (int) dn->dstat.st_uid);
+                else
+                        column += printf("%-8u %-8u",
+                                        (int) dn->dstat.st_uid,
+                                        (int) dn->dstat.st_gid);
+        }
+        if (all_fmt & (LIST_SIZE /*|LIST_DEV*/ )) {
+                if (S_ISBLK(dn->dstat.st_mode) || S_ISCHR(dn->dstat.st_mode)) {
+                        column += printf("%4u, %3u ",
+                                        (int) major(dn->dstat.st_rdev),
+                                        (int) minor(dn->dstat.st_rdev));
+                } else {
+                        if (all_fmt & LS_DISP_HR) {
+                                column += printf("%9s ",
+                                        make_human_readable_str(dn->dstat.st_size, 1, 0));
                         } else {
-                                if (all_fmt & LS_DISP_HR) {
-                                        column += printf("%9s ",
-                                                make_human_readable_str(dn->dstat.st_size, 1, 0));
-                                } else {
-                                        column += printf("%9"OFF_FMT"u ", (off_t) dn->dstat.st_size);
-                                }
+                                column += printf("%9"OFF_FMT"u ", (off_t) dn->dstat.st_size);
                         }
-                        break;
+                }
+        }
 #if ENABLE_FEATURE_LS_TIMESTAMPS
-                case LIST_FULLTIME:
-                        printf("%24.24s ", filetime);
-                        column += 25;
-                        break;
-                case LIST_DATE_TIME:
-                        if ((all_fmt & LIST_FULLTIME) == 0) {
-                                /* current_time_t ~== time(NULL) */
-                                age = current_time_t - ttime;
-                                printf("%6.6s ", filetime + 4);
-                                if (age < 3600L * 24 * 365 / 2 && age > -15 * 60) {
-                                        /* hh:mm if less than 6 months old */
-                                        printf("%5.5s ", filetime + 11);
-                                } else {
-                                        printf(" %4.4s ", filetime + 20);
-                                }
-                                column += 13;
+        if (all_fmt & LIST_FULLTIME)
+                column += printf("%24.24s ", filetime);
+        if (all_fmt & LIST_DATE_TIME)
+                if ((all_fmt & LIST_FULLTIME) == 0) {
+                        /* current_time_t ~== time(NULL) */
+                        age = current_time_t - ttime;
+                        printf("%6.6s ", filetime + 4);
+                        if (age < 3600L * 24 * 365 / 2 && age > -15 * 60) {
+                                /* hh:mm if less than 6 months old */
+                                printf("%5.5s ", filetime + 11);
+                        } else {
+                                printf(" %4.4s ", filetime + 20);
                         }
-                        break;
+                        column += 13;
+                }
 #endif
 #if ENABLE_SELINUX
-                case LIST_CONTEXT:
-                        column += printf("%-32s ", dn->sid ? dn->sid : "unknown");
-                        freecon(dn->sid);
-                        break;
+        if (all_fmt & LIST_CONTEXT) {
+                column += printf("%-32s ", dn->sid ? dn->sid : "unknown");
+                freecon(dn->sid);
+        }
 #endif
-                case LIST_FILENAME:
+        if (all_fmt & LIST_FILENAME) {
 #if ENABLE_FEATURE_LS_COLOR
-                        if (show_color) {
-                                info.st_mode = 0; /* for fgcolor() */
-                                lstat(dn->fullname, &info);
-                                printf("\033[%u;%um", bold(info.st_mode),
-                                                fgcolor(info.st_mode));
-                        }
+                if (show_color) {
+                        info.st_mode = 0; /* for fgcolor() */
+                        lstat(dn->fullname, &info);
+                        printf("\033[%u;%um", bold(info.st_mode),
+                                        fgcolor(info.st_mode));
+                }
 #endif
-                        column += print_name(dn->name);
-                        if (show_color) {
-                                printf("\033[0m");
-                        }
-                        break;
-                case LIST_SYMLINK:
-                        if (S_ISLNK(dn->dstat.st_mode)) {
-                                char *lpath = xmalloc_readlink_or_warn(dn->fullname);
-                                if (!lpath) break;
-                                printf(" -> ");
+                column += print_name(dn->name);
+                if (show_color) {
+                        printf("\033[0m");
+                }
+        }
+        if (all_fmt & LIST_SYMLINK) {
+                if (S_ISLNK(dn->dstat.st_mode) && lpath) {
+                        printf(" -> ");
 #if ENABLE_FEATURE_LS_FILETYPES || ENABLE_FEATURE_LS_COLOR
 #if ENABLE_FEATURE_LS_COLOR
-                                info.st_mode = 0; /* for fgcolor() */
+                        info.st_mode = 0; /* for fgcolor() */
 #endif
-                                if (stat(dn->fullname, &info) == 0) {
-                                        append = append_char(info.st_mode);
-                                }
+                        if (stat(dn->fullname, &info) == 0) {
+                                append = append_char(info.st_mode);
+                        }
 #endif
 #if ENABLE_FEATURE_LS_COLOR
-                                if (show_color) {
-                                        printf("\033[%u;%um", bold(info.st_mode),
-                                                   fgcolor(info.st_mode));
-                                }
+                        if (show_color) {
+                                printf("\033[%u;%um", bold(info.st_mode),
+                                           fgcolor(info.st_mode));
+                        }
 #endif
-                                column += print_name(lpath) + 4;
-                                if (show_color) {
-                                        printf("\033[0m");
-                                }
-                                free(lpath);
+                        column += print_name(lpath) + 4;
+                        if (show_color) {
+                                printf("\033[0m");
                         }
-                        break;
+                        free(lpath);
+                }
+        }
 #if ENABLE_FEATURE_LS_FILETYPES
-                case LIST_FILETYPE:
-                        if (append) {
-                                putchar(append);
-                                column++;
-                        }
-                        break;
-#endif
+        if (all_fmt & LIST_FILETYPE) {
+                if (append) {
+                        putchar(append);
+                        column++;
                 }
         }
+#endif
 
         return column;
 }
diff --git a/libbb/xreadlink.c b/libbb/xreadlink.c
index 6bff4beae..8d232f16b 100644
--- a/libbb/xreadlink.c
+++ b/libbb/xreadlink.c
@@ -91,7 +91,11 @@ char* FAST_FUNC xmalloc_readlink_or_warn(const char *path)
         char *buf = xmalloc_readlink(path);
         if (!buf) {
                 /* EINVAL => "file: Invalid argument" => puzzled user */
-                bb_error_msg("%s: cannot read link (not a symlink?)", path);
+                const char *errmsg = "not a symlink";
+                int err = errno;
+                if (err != EINVAL)
+                        errmsg = strerror(err);
+                bb_error_msg("%s: cannot read link: %s", path, errmsg);
         }
         return buf;
 }