gas/depend.c

   1 /* depend.c - Handle dependency tracking.
   2    Copyright (C) 1997-2020 Free Software Foundation, Inc.
   3
   4    This file is part of GAS, the GNU Assembler.
   5
   6    GAS is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3, or (at your option)
   9    any later version.
  10
  11    GAS is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GAS; see the file COPYING.  If not, write to the Free
  18    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  19    02110-1301, USA.  */
  20
  21 #include "as.h"
  22 #include "filenames.h"
  23
  24 /* The file to write to, or NULL if no dependencies being kept.  */
  25 static char * dep_file = NULL;
  26
  27 struct dependency
  28 {
  29   char * file;
  30   struct dependency * next;
  31 };
  32
  33 /* All the files we depend on.  */
  34 static struct dependency * dep_chain = NULL;
  35
  36 /* Current column in output file.  */
  37 static int column = 0;
  38
  39 static int quote_string_for_make (FILE *, const char *);
  40 static void wrap_output (FILE *, const char *, int);
  41
  42 /* Number of columns allowable.  */
  43 #define MAX_COLUMNS 72
  44 \f
  45 /* Start saving dependencies, to be written to FILENAME.  If this is
  46    never called, then dependency tracking is simply skipped.  */
  47
  48 void
  49 start_dependencies (char *filename)
  50 {
  51   dep_file = filename;
  52 }
  53
  54 /* Noticed a new filename, so try to register it.  */
  55
  56 void
  57 register_dependency (const char *filename)
  58 {
  59   struct dependency *dep;
  60
  61   if (dep_file == NULL)
  62     return;
  63
  64   for (dep = dep_chain; dep != NULL; dep = dep->next)
  65     {
  66       if (!filename_cmp (filename, dep->file))
  67         return;
  68     }
  69
  70   dep = XNEW (struct dependency);
  71   dep->file = xstrdup (filename);
  72   dep->next = dep_chain;
  73   dep_chain = dep;
  74 }
  75
  76 /* Quote a file name the way `make' wants it, and print it to FILE.
  77    If FILE is NULL, do no printing, but return the length of the
  78    quoted string.
  79
  80    This code is taken from gcc with only minor changes.  */
  81
  82 static int
  83 quote_string_for_make (FILE *file, const char *src)
  84 {
  85   const char *p = src;
  86   int i = 0;
  87
  88   for (;;)
  89     {
  90       char c = *p++;
  91
  92       switch (c)
  93         {
  94         case '\0':
  95         case ' ':
  96         case '\t':
  97           {
  98             /* GNU make uses a weird quoting scheme for white space.
  99                A space or tab preceded by 2N+1 backslashes represents
 100                N backslashes followed by space; a space or tab
 101                preceded by 2N backslashes represents N backslashes at
 102                the end of a file name; and backslashes in other
 103                contexts should not be doubled.  */
 104             const char *q;
 105
 106             for (q = p - 1; src < q && q[-1] == '\\'; q--)
 107               {
 108                 if (file)
 109                   putc ('\\', file);
 110                 i++;
 111               }
 112           }
 113           if (!c)
 114             return i;
 115           if (file)
 116             putc ('\\', file);
 117           i++;
 118           goto ordinary_char;
 119
 120         case '$':
 121           if (file)
 122             putc (c, file);
 123           i++;
 124           /* Fall through.  */
 125           /* This can mishandle things like "$(" but there's no easy fix.  */
 126         default:
 127         ordinary_char:
 128           /* This can mishandle characters in the string "\0\n%*?[\\~";
 129              exactly which chars are mishandled depends on the `make' version.
 130              We know of no portable solution for this;
 131              even GNU make 3.76.1 doesn't solve the problem entirely.
 132              (Also, '\0' is mishandled due to our calling conventions.)  */
 133           if (file)
 134             putc (c, file);
 135           i++;
 136           break;
 137         }
 138     }
 139 }
 140
 141 /* Append some output to the file, keeping track of columns and doing
 142    wrapping as necessary.  */
 143
 144 static void
 145 wrap_output (FILE *f, const char *string, int spacer)
 146 {
 147   int len = quote_string_for_make (NULL, string);
 148
 149   if (len == 0)
 150     return;
 151
 152   if (column
 153       && (MAX_COLUMNS
 154           - 1 /* spacer */
 155           - 2 /* ` \'   */
 156           < column + len))
 157     {
 158       fprintf (f, " \\\n ");
 159       column = 0;
 160       if (spacer == ' ')
 161         spacer = '\0';
 162     }
 163
 164   if (spacer == ' ')
 165     {
 166       putc (spacer, f);
 167       ++column;
 168     }
 169
 170   quote_string_for_make (f, string);
 171   column += len;
 172
 173   if (spacer == ':')
 174     {
 175       putc (spacer, f);
 176       ++column;
 177     }
 178 }
 179
 180 /* Print dependency file.  */
 181
 182 void
 183 print_dependencies (void)
 184 {
 185   FILE *f;
 186   struct dependency *dep;
 187
 188   if (dep_file == NULL)
 189     return;
 190
 191   f = fopen (dep_file, FOPEN_WT);
 192   if (f == NULL)
 193     {
 194       as_warn (_("can't open `%s' for writing"), dep_file);
 195       return;
 196     }
 197
 198   column = 0;
 199   wrap_output (f, out_file_name, ':');
 200   for (dep = dep_chain; dep != NULL; dep = dep->next)
 201     wrap_output (f, dep->file, ' ');
 202
 203   putc ('\n', f);
 204
 205   if (fclose (f))
 206     as_warn (_("can't close `%s'"), dep_file);
 207 }