Add --debug-prefix-map option

Adds an option to remap file prefixes in output object files. This is
analogous to the "-fdebug-prefix-map" option in GCC, and allows files to
be built in a reproducible manner regardless of the build directory.

Signed-off-by: Joshua Watt <[email protected]>

Author: JPEWdev

asm/nasm.c

@@ -886,7 +886,8 @@ enum text_options {
     OPT_DEBUG,
     OPT_INFO,
     OPT_REPRODUCIBLE,
-    OPT_BITS
+    OPT_BITS,
+    OPT_DEBUG_PREFIX_MAP
 };
 enum need_arg {
     ARG_NO,
@@ -925,6 +926,7 @@ static const struct textargs textopts[] = {
     {"debug",    OPT_DEBUG, ARG_MAYBE, 0},
     {"reproducible", OPT_REPRODUCIBLE, ARG_NO, 0},
     {"bits",     OPT_BITS, ARG_YES, 0},
+    {"debug-prefix-map", OPT_DEBUG_PREFIX_MAP, ARG_YES, 0},
     {NULL, OPT_BOGUS, ARG_NO, 0}
 };
 
@@ -1305,6 +1307,26 @@ static bool process_arg(char *p, char *q, int pass)
                 case OPT_REPRODUCIBLE:
                     reproducible = true;
                     break;
+                case OPT_DEBUG_PREFIX_MAP: {
+                    struct debug_prefix_list *d;
+                    char *c;
+                    c = strchr(param, '=');
+
+                    if (!c) {
+                        nasm_error(ERR_NONFATAL | ERR_NOFILE | ERR_USAGE,
+                                   "option `--%s' must be of the form `BASE=DEST'", p);
+                        break;
+                    }
+
+                    *c = '\0';
+                    d = nasm_malloc(sizeof(*d));
+                    d->next = debug_prefixes;
+                    d->base = nasm_strdup(param);
+                    d->dest = nasm_strdup(c + 1);
+                    debug_prefixes = d;
+                    *c = '=';
+                    }
+                    break;
                 case OPT_HELP:
                     /* Allow --help topic without *requiring* topic */
                     if (!param)
@@ -2031,6 +2053,8 @@ static void help(FILE *out, const char *what)
             "    --lprefix str  prepend the given string to local symbols\n"
             "    --lpostfix str append the given string to local symbols\n"
             "    --reproducible attempt to produce run-to-run identical output\n"
+            "    --debug-prefix-map base=dest\n"
+            "                   remap paths starting with 'base' to 'dest' in output files\n"
             , out);
     }
     if (help_optor(with, HW_LIMIT)) {

include/nasmlib.h

@@ -334,10 +334,19 @@ static inline const char *nasm_digit_chars(bool ucase)
  */
 int32_t seg_alloc(void);
 
+struct debug_prefix_list {
+    struct debug_prefix_list *next;
+    char *base;
+    char *dest;
+};
+
+extern struct debug_prefix_list *debug_prefixes;
+
 /*
  * Add/replace or remove an extension to the end of a filename
  */
 const char *filename_set_extension(const char *inname, const char *extension);
+char *filename_debug_remap(char *dest, char const *inname, size_t len);
 
 /*
  * Utility macros...

nasm.txt

@@ -147,6 +147,10 @@ OPTIONS
 	Prepend or append (respectively) the given argument to all global or
 	extern variables.
 
+--debug-prefix-map 'BASE=DEST'::
+    Map file names beginning with 'BASE' to 'DEST' when encoding them in
+    output object files.
+
 SYNTAX
 ------
 This man page does not fully describe the syntax of *nasm*'s assembly language,

nasmlib/filename.c

@@ -9,6 +9,8 @@
 #include "nasmlib.h"
 #include "error.h"
 
+struct debug_prefix_list *debug_prefixes = NULL;
+
 /*
  * Add/modify a filename extension, assumed to be a period-delimited
  * field at the very end of the filename.  Returns a newly allocated
@@ -31,3 +33,21 @@ const char *filename_set_extension(const char *inname, const char *extension)
 
     return p;
 }
+
+char *filename_debug_remap(char *dest, char const *in, size_t len)
+{
+    struct debug_prefix_list *d;
+    size_t n;
+
+    for (d = debug_prefixes; d != NULL; d = d->next) {
+        n = strlen(d->base);
+        if (strncmp(in, d->base, n) == 0) {
+            strlcpy(dest, d->dest, len);
+            strlcat(dest, &in[n], len);
+            return dest;
+        }
+    }
+
+    strlcpy(dest, in, len);
+    return dest;
+}

output/outas86.c

@@ -71,6 +71,7 @@ static struct SAA *strs;
 static size_t strslen;
 
 static int as86_reloc_size;
+static char filename[FILENAME_MAX];
 
 static void as86_write(void);
 static void as86_write_section(struct Section *, int);
@@ -101,7 +102,7 @@ static void as86_init(void)
     strslen = 0;
 
     /* as86 module name = input file minus extension */
-    as86_add_string(filename_set_extension(inname, ""));
+    as86_add_string(filename_debug_remap(filename, filename_set_extension(inname, ""), sizeof(filename)));
 }
 
 static void as86_cleanup(void)

output/outcoff.c

@@ -1239,10 +1239,10 @@ static void coff_write_symbols(void)
      */
     coff_symbol(".file", 0L, 0L, -2, 0, 0x67, 1);
     if (reproducible)
-        memset(filename, 0, 18);
+        memset(filename, 0, sizeof(filename));
     else
-        strncpy(filename, inname, 18);
-    nasm_write(filename, 18, ofile);
+        filename_debug_remap(filename, inname, sizeof(filename));
+    nasm_write(filename, sizeof(filename), ofile);
 
     /*
      * The section records, with their auxiliaries.

output/outelf.c

@@ -516,8 +516,8 @@ static void elf_init(void)
     const char * const *p;
     const char * cur_path = nasm_realpath(inname);
 
-    strlcpy(elf_module, inname, sizeof(elf_module));
-    strlcpy(elf_dir, nasm_dirname(cur_path), sizeof(elf_dir));
+    filename_debug_remap(elf_module, inname, sizeof(elf_module));
+    filename_debug_remap(elf_dir, nasm_dirname(cur_path), sizeof(elf_dir));
     sects = NULL;
     nsects = sectlen = 0;
     syms = saa_init((int32_t)sizeof(struct elf_symbol));

output/outieee.c

@@ -178,7 +178,7 @@ static void ieee_unqualified_name(char *, char *);
  */
 static void ieee_init(void)
 {
-    strlcpy(ieee_infile, inname, sizeof(ieee_infile));
+    filename_debug_remap(ieee_infile, inname, sizeof(ieee_infile));
     any_segs = false;
     fpubhead = NULL;
     fpubtail = &fpubhead;

output/outobj.c

@@ -656,7 +656,7 @@ static const char *get_default_class(const char *segment)
 
 static void obj_init(void)
 {
-    strlcpy(obj_infile, inname, sizeof(obj_infile));
+    filename_debug_remap(obj_infile, inname, sizeof(obj_infile));
     first_seg = seg_alloc();
     any_segs = false;
     fpubhead = NULL;

test/elfdebugprefix.asm

@@ -0,0 +1,6 @@
+;Testname=unoptimized; Arguments=-O0 --debug-prefix-map elf=ELF -felf -oelfdebugprefix.o; Files=stdout stderr elfdebugprefix.o; Validate=readelf --wide --symbols elfdebugprefix.o | grep 'FILE.*ELFdebugprefix.asm'
+
+	  SECTION .text
+test:			; [1]
+	  ret
+