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.

[ hpa: this still needs to be documented in doc/running.src. ]

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>

Author: JPEWdev

asm/nasm.c

@@ -42,11 +42,17 @@ struct forwrefinfo {            /* info held on forward refs. */
     int operand;
 };
 
+struct debug_prefix_list {
+    struct debug_prefix_list *next;
+    char *base;
+    char *dest;
+};
+
 const char *_progname;
 
 static void open_and_process_respfile(char *, int);
 static void parse_cmdline(int, char **, int);
-static void assemble_file(const char *, struct strlist *);
+static void assemble_file(const char *, char const *, struct strlist *);
 static void help(FILE *out, const char *what);
 
 static bool using_debug_info;
@@ -81,6 +87,8 @@ FILE *ofile = NULL;
 enum optimization optimizing = OPTIM_DEFAULT;
 static int cmd_sb = 16;    /* by default */
 
+static struct debug_prefix_list *debug_prefixes = NULL;
+
 iflag_t cpu, cmd_cpu;
 
 struct location location;
@@ -721,7 +729,7 @@ int main(int argc, char **argv)
             if (depend_missing_ok)
                 pp_include_path(NULL);    /* "assume generated" */
 
-            pp_reset(get_filename(FN_INFILE), PP_DEPS, depend_list);
+            pp_reset(get_filename(FN_INFILE), get_filename(FN_MAPPED_INFILE), PP_DEPS, depend_list);
             ofile = NULL;
             while ((line = pp_getline()))
                 nasm_free(line);
@@ -747,7 +755,7 @@ int main(int argc, char **argv)
             location.known = false;
 
             _pass_type = PASS_PREPROC;
-            pp_reset(get_filename(FN_INFILE), PP_PREPROC, depend_list);
+            pp_reset(get_filename(FN_INFILE), get_filename(FN_MAPPED_INFILE), PP_PREPROC, depend_list);
             error_pass_start(true);
 
             while ((line = pp_getline())) {
@@ -808,7 +816,7 @@ int main(int argc, char **argv)
         ofmt->init();
         dfmt->init();
 
-        assemble_file(get_filename(FN_INFILE), depend_list);
+        assemble_file(get_filename(FN_INFILE), get_filename(FN_MAPPED_INFILE), depend_list);
 
         if (!terminate_after_phase()) {
             ofmt->cleanup();
@@ -864,6 +872,30 @@ static char *get_param(char *p, char *q, bool *advance)
     return r;
 }
 
+/*
+ * Apply debug prefix mappings to a path buffer
+ */
+static char *debug_prefix_remap(char const* path)
+{
+    struct debug_prefix_list *d;
+    size_t n;
+
+    for (d = debug_prefixes; d != NULL; d = d->next) {
+        n = strlen(d->base);
+        if (strncmp(path, d->base, n) == 0) {
+            size_t prefix_len = strlen(d->dest);
+            size_t suffix_len = strlen(path) - n;
+            size_t len = prefix_len + suffix_len + 1;
+            char* out = nasm_malloc(len);
+            strlcpy(out, d->dest, len);
+            strlcpy(&out[prefix_len], &path[n], len - prefix_len);
+            return out;
+        }
+    }
+
+    return nasm_strdup(path);
+}
+
 /*
  * Convert a string to a POSIX make-safe form; returns a newly allocated
  * string.
@@ -1030,7 +1062,8 @@ enum text_options {
     OPT_DEBUG,
     OPT_INFO,
     OPT_REPRODUCIBLE,
-    OPT_BITS
+    OPT_BITS,
+    OPT_DEBUG_PREFIX_MAP
 };
 enum need_arg {
     ARG_NO,
@@ -1069,6 +1102,7 @@ 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}
 };
 
@@ -1455,6 +1489,26 @@ 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)
@@ -1672,6 +1726,8 @@ static void parse_cmdline(int argc, char **argv, int pass)
     if (!get_filename(FN_INFILE))
         nasm_fatalf(ERR_USAGE, "no input file specified");
 
+    set_filename(FN_MAPPED_INFILE, debug_prefix_remap(get_filename(FN_INFILE)));
+
     check_overwrite_files();
 
     open_errfile(get_filename(FN_ERRFILE));
@@ -1724,7 +1780,7 @@ void print_final_report(bool failure)
     }
 }
 
-static void assemble_file(const char *fname, struct strlist *depend_list)
+static void assemble_file(const char *fname, char const* mapped_fname, struct strlist *depend_list)
 {
     static int64_t stall_count = 0; /* Make sure we make forward progress... */
     char *line;
@@ -1814,7 +1870,7 @@ static void assemble_file(const char *fname, struct strlist *depend_list)
             location.known = true;
         ofmt->reset();
         switch_segment(ofmt->section(NULL, &globl.bits));
-        pp_reset(fname, PP_NORMAL, depend_list);
+        pp_reset(fname, mapped_fname, PP_NORMAL, depend_list);
 
         globallineno = 0;
 
@@ -2205,6 +2261,8 @@ 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_is(with, HW_LIMIT)) {

asm/preproc.c

@@ -8638,7 +8638,7 @@ static void pp_reset_stdmac(enum preproc_mode mode)
     define_smacro("__?PASS?__", true, make_tok_num(NULL, apass), NULL);
 }
 
-void pp_reset(const char *file, enum preproc_mode mode,
+void pp_reset(const char *file, char const* mapped_fname, enum preproc_mode mode,
               struct strlist *dep_list)
 {
     cstk = NULL;
@@ -8677,7 +8677,7 @@ void pp_reset(const char *file, enum preproc_mode mode,
 	nasm_fatalf(ERR_NOFILE, "unable to open input file `%s'%s%s",
                     file, errno ? " " : "", errno ? strerror(errno) : "");
     }
-    src_set(0, file);
+    src_set(0, mapped_fname);
     istk->where = src_where();
     istk->lineinc = 1;
 

common/files.c

@@ -7,6 +7,7 @@
 
 static const char * const filename_names[FN_NFILES] = {
     "input",
+    "mapped-input",
     "output",
     "error",
     "list",
@@ -44,7 +45,7 @@ void check_overwrite_files(void)
     if (!inname)
         return;
 
-    for (fn = FN_INFILE+1; fn < FN_NFILES; fn++) {
+    for (fn = FN_INFILE+2; fn < FN_NFILES; fn++) {
         const char *outname = get_filename(fn);
         if (outname && !strcmp(inname, outname)) {
             nasm_fatal("%s file would overwrite input file",

include/files.h

@@ -14,6 +14,7 @@
 enum filenames {
     /* These two entries must be first, in this order */
     FN_INFILE,                  /* Primary input file */
+    FN_MAPPED_INFILE,           /* Debug mapped input file */
     FN_OUTFILE,                 /* Primary output file */
 
     FN_ERRFILE,                 /* Error message file */

include/nasm.h

@@ -458,7 +458,7 @@ void pp_init(enum preproc_opt opt);
  * of the pass, an error reporting function, an evaluator
  * function, and a listing generator to talk to.
  */
-void pp_reset(const char *file, enum preproc_mode mode,
+void pp_reset(const char *file, const char* mapped_fname, enum preproc_mode mode,
               struct strlist *deplist);
 
 /*

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,

output/outas86.c

@@ -104,7 +104,7 @@ static void as86_init(void)
     strslen = 0;
 
     /* as86 module name = input file minus extension */
-    module_name = filename_set_extension(get_filename(FN_INFILE), "");
+    module_name = filename_set_extension(get_filename(FN_MAPPED_INFILE), "");
     as86_add_string(module_name);
     nasm_free(module_name);
 }

output/outcoff.c

@@ -1342,7 +1342,7 @@ static void coff_write_symbols(void)
     if (reproducible)
         memset(filename, 0, 18);
     else
-        strncpy(filename, get_filename(FN_INFILE), 18);
+        strncpy(filename, get_filename(FN_MAPPED_INFILE), 18);
     nasm_write(filename, 18, ofile);
 
     /*

output/outelf.c

@@ -511,7 +511,7 @@ static void elf64_init(void)
 
 static void elf_populate_dirs(void)
 {
-    const char * const infile = get_filename(FN_INFILE);
+    const char * const infile = get_filename(FN_MAPPED_INFILE);
     char *cur_path = nasm_realpath(infile);
     char *dir_name = nasm_dirname(cur_path);
 

output/outieee.c

@@ -179,7 +179,7 @@ static void ieee_unqualified_name(char *, char *);
  */
 static void ieee_init(void)
 {
-    strlcpy(ieee_infile, get_filename(FN_INFILE), sizeof(ieee_infile));
+    strlcpy(ieee_infile, get_filename(FN_MAPPED_INFILE), sizeof(ieee_infile));
     any_segs = false;
     fpubhead = NULL;
     fpubtail = &fpubhead;