From: Richard W.M. Jones Date: Mon, 29 Jun 2009 10:46:19 +0000 (+0100) Subject: Implement "head", "head-n", "tail", "tail-n" commands. X-Git-Tag: 1.0.54~14 X-Git-Url: http://git.annexia.org/?a=commitdiff_plain;h=3854bbdecd1c089959fb812a739b84a96c05fbbf;p=libguestfs.git Implement "head", "head-n", "tail", "tail-n" commands. These commands let you view parts of a large file without passing the whole file over the network connection. --- diff --git a/TODO b/TODO index 20f5ca0..7696daa 100644 --- a/TODO +++ b/TODO @@ -117,7 +117,6 @@ Supermin appliance should be moved into febootstrap. Extra commands / functionality: General glibc / core programs: - head, tail chgrp grep (do it locally using pipe?) dd (?) diff --git a/daemon/Makefile.am b/daemon/Makefile.am index b58ec3d..4228ad0 100644 --- a/daemon/Makefile.am +++ b/daemon/Makefile.am @@ -39,6 +39,7 @@ guestfsd_SOURCES = \ glob.c \ grub.c \ guestfsd.c \ + headtail.c \ hexdump.c \ ls.c \ lvm.c \ diff --git a/daemon/headtail.c b/daemon/headtail.c new file mode 100644 index 0000000..b522c55 --- /dev/null +++ b/daemon/headtail.c @@ -0,0 +1,107 @@ +/* libguestfs - the guestfsd daemon + * Copyright (C) 2009 Red Hat Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include + +#include +#include +#include +#include + +#include "../src/guestfs_protocol.h" +#include "daemon.h" +#include "actions.h" + +static char ** +headtail (const char *prog, const char *flag, const char *n, char *path) +{ + char *buf; + char *out, *err; + int r, len; + char **lines; + + NEED_ROOT (NULL); + ABS_PATH (path, NULL); + + /* Make the path relative to /sysroot. */ + len = strlen (path) + 9; + buf = malloc (len); + if (!buf) { + reply_with_perror ("malloc"); + return NULL; + } + snprintf (buf, len, "/sysroot%s", path); + + r = command (&out, &err, prog, flag, n, buf, NULL); + free (buf); + if (r == -1) { + reply_with_error ("%s %s %s: %s", prog, flag, n, err); + free (out); + free (err); + return NULL; + } + + free (err); + +#if 0 + /* Split it at the first whitespace. */ + len = strcspn (out, " \t\n"); + out[len] = '\0'; +#endif + + lines = split_lines (out); + free (out); + if (lines == NULL) return NULL; + + return lines; +} + +char ** +do_head (char *path) +{ + return headtail ("head", "-n", "10", path); +} + +char ** +do_tail (char *path) +{ + return headtail ("tail", "-n", "10", path); +} + +char ** +do_head_n (int n, char *path) +{ + char nbuf[16]; + + snprintf (nbuf, sizeof nbuf, "%d", n); + + return headtail ("head", "-n", nbuf, path); +} + +char ** +do_tail_n (int n, char *path) +{ + char nbuf[16]; + + if (n >= 0) + snprintf (nbuf, sizeof nbuf, "%d", n); + else + snprintf (nbuf, sizeof nbuf, "+%d", -n); + + return headtail ("tail", "-n", nbuf, path); +} diff --git a/src/generator.ml b/src/generator.ml index aecb152..abc73da 100755 --- a/src/generator.ml +++ b/src/generator.ml @@ -2500,6 +2500,64 @@ C external command."); This command counts the characters in a file, using the C external command."); + ("head", (RStringList "lines", [String "path"]), 121, [ProtocolLimitWarning], + [InitBasicFS, Always, TestOutputList ( + [["mount_vfs"; "ro"; "squashfs"; "/dev/sdd"; "/"]; + ["head"; "/10klines"]], ["0abcdefghijklmnopqrstuvwxyz";"1abcdefghijklmnopqrstuvwxyz";"2abcdefghijklmnopqrstuvwxyz";"3abcdefghijklmnopqrstuvwxyz";"4abcdefghijklmnopqrstuvwxyz";"5abcdefghijklmnopqrstuvwxyz";"6abcdefghijklmnopqrstuvwxyz";"7abcdefghijklmnopqrstuvwxyz";"8abcdefghijklmnopqrstuvwxyz";"9abcdefghijklmnopqrstuvwxyz"])], + "return first 10 lines of a file", + "\ +This command returns up to the first 10 lines of a file as +a list of strings."); + + ("head_n", (RStringList "lines", [Int "nrlines"; String "path"]), 122, [ProtocolLimitWarning], + [InitBasicFS, Always, TestOutputList ( + [["mount_vfs"; "ro"; "squashfs"; "/dev/sdd"; "/"]; + ["head_n"; "3"; "/10klines"]], ["0abcdefghijklmnopqrstuvwxyz";"1abcdefghijklmnopqrstuvwxyz";"2abcdefghijklmnopqrstuvwxyz"]); + InitBasicFS, Always, TestOutputList ( + [["mount_vfs"; "ro"; "squashfs"; "/dev/sdd"; "/"]; + ["head_n"; "-9997"; "/10klines"]], ["0abcdefghijklmnopqrstuvwxyz";"1abcdefghijklmnopqrstuvwxyz";"2abcdefghijklmnopqrstuvwxyz"]); + InitBasicFS, Always, TestOutputList ( + [["mount_vfs"; "ro"; "squashfs"; "/dev/sdd"; "/"]; + ["head_n"; "0"; "/10klines"]], [])], + "return first N lines of a file", + "\ +If the parameter C is a positive number, this returns the first +C lines of the file C. + +If the parameter C is a negative number, this returns lines +from the file C, excluding the last C lines. + +If the parameter C is zero, this returns an empty list."); + + ("tail", (RStringList "lines", [String "path"]), 123, [ProtocolLimitWarning], + [InitBasicFS, Always, TestOutputList ( + [["mount_vfs"; "ro"; "squashfs"; "/dev/sdd"; "/"]; + ["tail"; "/10klines"]], ["9990abcdefghijklmnopqrstuvwxyz";"9991abcdefghijklmnopqrstuvwxyz";"9992abcdefghijklmnopqrstuvwxyz";"9993abcdefghijklmnopqrstuvwxyz";"9994abcdefghijklmnopqrstuvwxyz";"9995abcdefghijklmnopqrstuvwxyz";"9996abcdefghijklmnopqrstuvwxyz";"9997abcdefghijklmnopqrstuvwxyz";"9998abcdefghijklmnopqrstuvwxyz";"9999abcdefghijklmnopqrstuvwxyz"])], + "return last 10 lines of a file", + "\ +This command returns up to the last 10 lines of a file as +a list of strings."); + + ("tail_n", (RStringList "lines", [Int "nrlines"; String "path"]), 124, [ProtocolLimitWarning], + [InitBasicFS, Always, TestOutputList ( + [["mount_vfs"; "ro"; "squashfs"; "/dev/sdd"; "/"]; + ["tail_n"; "3"; "/10klines"]], ["9997abcdefghijklmnopqrstuvwxyz";"9998abcdefghijklmnopqrstuvwxyz";"9999abcdefghijklmnopqrstuvwxyz"]); + InitBasicFS, Always, TestOutputList ( + [["mount_vfs"; "ro"; "squashfs"; "/dev/sdd"; "/"]; + ["tail_n"; "-9998"; "/10klines"]], ["9997abcdefghijklmnopqrstuvwxyz";"9998abcdefghijklmnopqrstuvwxyz";"9999abcdefghijklmnopqrstuvwxyz"]); + InitBasicFS, Always, TestOutputList ( + [["mount_vfs"; "ro"; "squashfs"; "/dev/sdd"; "/"]; + ["tail_n"; "0"; "/10klines"]], [])], + "return last N lines of a file", + "\ +If the parameter C is a positive number, this returns the last +C lines of the file C. + +If the parameter C is a negative number, this returns lines +from the file C, starting with the C<-nrlines>th line. + +If the parameter C is zero, this returns an empty list."); + ] let all_functions = non_daemon_functions @ daemon_functions