libbb/appletlib.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Support for main() which needs to end up in libbusybox, not busybox,
   4  * if one builds libbusybox.
   5  *
   6  * Copyright (C) 2007 Denys Vlasenko <vda.linux@googlemail.com>
   7  *
   8  * Licensed under GPLv2, see file License in this tarball for details.
   9  */
  10
  11 #include <assert.h>
  12 #include "busybox.h"
  13
  14
  15 /* Declare <applet>_main() */
  16 #define PROTOTYPES
  17 #include "applets.h"
  18 #undef PROTOTYPES
  19
  20 #if ENABLE_SHOW_USAGE && !ENABLE_FEATURE_COMPRESS_USAGE
  21 /* Define usage_messages[] */
  22 static const char usage_messages[] ALIGN1 = ""
  23 #define MAKE_USAGE
  24 #include "usage.h"
  25 #include "applets.h"
  26 ;
  27 #undef MAKE_USAGE
  28 #else
  29 #define usage_messages 0
  30 #endif /* SHOW_USAGE */
  31
  32 /* Define struct bb_applet applets[] */
  33 #include "applets.h"
  34
  35 #if ENABLE_FEATURE_SH_STANDALONE
  36 /* -1 because last entry is NULL */
  37 const unsigned short NUM_APPLETS = ARRAY_SIZE(applets) - 1;
  38 #endif
  39
  40
  41 #if ENABLE_FEATURE_COMPRESS_USAGE
  42
  43 #include "usage_compressed.h"
  44 #include "unarchive.h"
  45
  46 static const char *unpack_usage_messages(void)
  47 {
  48         char *outbuf = NULL;
  49         bunzip_data *bd;
  50         int i;
  51
  52         i = start_bunzip(&bd,
  53                         /* src_fd: */ -1,
  54                         /* inbuf:  */ packed_usage,
  55                         /* len:    */ sizeof(packed_usage));
  56         /* read_bunzip can longjmp to start_bunzip, and ultimately
  57          * end up here with i != 0 on read data errors! Not trivial */
  58         if (!i) {
  59                 /* Cannot use xmalloc: will leak bd in NOFORK case! */
  60                 outbuf = malloc_or_warn(SIZEOF_usage_messages);
  61                 if (outbuf)
  62                         read_bunzip(bd, outbuf, SIZEOF_usage_messages);
  63         }
  64         dealloc_bunzip(bd);
  65         return outbuf;
  66 }
  67 #define dealloc_usage_messages(s) free(s)
  68
  69 #else
  70
  71 #define unpack_usage_messages() usage_messages
  72 #define dealloc_usage_messages(s) ((void)(s))
  73
  74 #endif /* FEATURE_COMPRESS_USAGE */
  75
  76
  77 void bb_show_usage(void)
  78 {
  79         if (ENABLE_SHOW_USAGE) {
  80                 const char *format_string;
  81                 const char *p;
  82                 const char *usage_string = p = unpack_usage_messages();
  83                 const struct bb_applet *ap = find_applet_by_name(applet_name);
  84                 int i;
  85
  86                 if (!ap) /* never happens, paranoia */
  87                         xfunc_die();
  88
  89                 i = ap - applets;
  90                 while (i) {
  91                         while (*p++) continue;
  92                         i--;
  93                 }
  94
  95                 fprintf(stderr, "%s multi-call binary\n", bb_banner);
  96                 format_string = "\nUsage: %s %s\n\n";
  97                 if (*p == '\b')
  98                         format_string = "\nNo help available.\n\n";
  99                 fprintf(stderr, format_string, applet_name, p);
 100                 dealloc_usage_messages((char*)usage_string);
 101         }
 102         xfunc_die();
 103 }
 104
 105
 106 static int applet_name_compare(const void *name, const void *vapplet)
 107 {
 108         const struct bb_applet *applet = vapplet;
 109
 110         return strcmp(name, applet->name);
 111 }
 112
 113 const struct bb_applet *find_applet_by_name(const char *name)
 114 {
 115         /* Do a binary search to find the applet entry given the name. */
 116         return bsearch(name, applets, ARRAY_SIZE(applets)-1, sizeof(applets[0]),
 117                                 applet_name_compare);
 118 }
 119
 120
 121 #ifdef __GLIBC__
 122 /* Make it reside in R/W memory: */
 123 int *const bb_errno __attribute__ ((section (".data")));
 124 #endif
 125
 126 void bbox_prepare_main(char **argv)
 127 {
 128 #ifdef __GLIBC__
 129         (*(int **)&bb_errno) = __errno_location();
 130 #endif
 131
 132         /* Set locale for everybody except 'init' */
 133         if (ENABLE_LOCALE_SUPPORT && getpid() != 1)
 134                 setlocale(LC_ALL, "");
 135
 136 #if ENABLE_FEATURE_INDIVIDUAL
 137         /* Redundant for busybox (run_applet_and_exit covers that case)
 138          * but needed for "individual applet" mode */
 139         if (argv[1] && strcmp(argv[1], "--help") == 0)
 140                 bb_show_usage();
 141 #endif
 142 }