1 /* depend.c - Handle dependency tracking.
2    Copyright (C) 1997-2024 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 
45 /* Start saving dependencies, to be written to FILENAME.  If this is
46    never called, then dependency tracking is simply skipped.  */
47 
48 void
start_dependencies(char * filename)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
register_dependency(const char * filename)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
quote_string_for_make(FILE * file,const char * src)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
wrap_output(FILE * f,const char * string,int spacer)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
print_dependencies(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 }
208