Support #pragma dynexport on OS X.

R=rsc
CC=golang-dev
https://golang.org/cl/733041

diff --git a/src/cmd/ld/macho.c b/src/cmd/ld/macho.c
index 7a0be67119107104556d8cc753550f73a0a36534..3e33fe494e683e1e4bcbb45162a58130fa2197ee 100644 (file)
--- a/src/cmd/ld/macho.c
+++ b/src/cmd/ld/macho.c
@@ -105,6 +105,14 @@ static uchar *strtab;
 static uint32 nstrtab;
 static uint32 mstrtab;
 
+struct Expsym
+{
+       int     off;
+       Sym*    s;
+} *expsym;
+static int nexpsym;
+static int nimpsym;
+
 static char **dylib;
 static int ndylib;
 
@@ -264,11 +272,12 @@ needlib(char *name)
 void
 domacho(void)
 {
-       int h, nsym, ptrsize;
+       int h, ptrsize, t;
        char *p;
        uchar *dat;
        uint32 x;
        Sym *s;
+       Sym **impsym;
 
        ptrsize = 4;
        if(macho64)
@@ -278,17 +287,26 @@ domacho(void)
        if(!debug['d'])
                *(char*)grow(&strtab, &nstrtab, &mstrtab, 2) = ' ';
 
-       nsym = 0;
+       impsym = nil;
        for(h=0; h<NHASH; h++) {
                for(s=hash[h]; s!=S; s=s->link) {
-                       if(!s->reachable || (s->type != SDATA && s->type != SBSS) || s->dynimpname == nil)
+                       if(!s->reachable || (s->type != STEXT && s->type != SDATA && s->type != SBSS) || s->dynimpname == nil)
                                continue;
                        if(debug['d']) {
                                diag("cannot use dynamic loading and -d");
                                errorexit();
                        }
-                       s->type = SMACHO;
-                       s->value = nsym*ptrsize;
+                       if(!s->dynexport) {
+                               if(nimpsym%32 == 0) {
+                                       impsym = realloc(impsym, (nimpsym+32)*sizeof impsym[0]);
+                                       if(impsym == nil) {
+                                               diag("out of memory");
+                                               errorexit();
+                                       }
+                               }
+                               impsym[nimpsym++] = s;
+                               continue;
+                       }
 
                        /* symbol table entry - darwin still puts _ prefixes on all C symbols */
                        x = nstrtab;
@@ -301,29 +319,73 @@ domacho(void)
                        dat[1] = x>>8;
                        dat[2] = x>>16;
                        dat[3] = x>>24;
-                       dat[4] = 0x01;  // type: N_EXT - external symbol
 
-                       if(needlib(s->dynimplib)) {
-                               if(ndylib%32 == 0) {
-                                       dylib = realloc(dylib, (ndylib+32)*sizeof dylib[0]);
-                                       if(dylib == nil) {
-                                               diag("out of memory");
-                                               errorexit();
-                                       }
+                       dat[4] = 0x0f;  // type: N_SECT | N_EXT - external, defined in sect
+                       switch(s->type) {
+                       default:
+                       case STEXT:
+                               t = 1;
+                               break;
+                       case SDATA:
+                               t = 2;
+                               break;
+                       case SBSS:
+                               t = 4;
+                               break;
+                       }
+                       dat[5] = t;     // sect: section number
+
+                       if (nexpsym%32 == 0) {
+                               expsym = realloc(expsym, (nexpsym+32)*sizeof expsym[0]);
+                               if (expsym == nil) {
+                                       diag("out of memory");
+                                       errorexit();
                                }
-                               dylib[ndylib++] = s->dynimplib;
                        }
-                       nsym++;
+                       expsym[nexpsym].off = nlinkdata - ptrsize;
+                       expsym[nexpsym++].s = s;
                }
        }
 
+       for(h=0; h<nimpsym; h++) {
+               s = impsym[h];
+               s->type = SMACHO;
+               s->value = (nexpsym+h) * ptrsize;
+
+               /* symbol table entry - darwin still puts _ prefixes on all C symbols */
+               x = nstrtab;
+               p = grow(&strtab, &nstrtab, &mstrtab, 1+strlen(s->dynimpname)+1);
+               *p++ = '_';
+               strcpy(p, s->dynimpname);
+
+               dat = grow(&linkdata, &nlinkdata, &mlinkdata, 8+ptrsize);
+               dat[0] = x;
+               dat[1] = x>>8;
+               dat[2] = x>>16;
+               dat[3] = x>>24;
+
+               dat[4] = 0x01;  // type: N_EXT - external symbol
+
+               if(needlib(s->dynimplib)) {
+                       if(ndylib%32 == 0) {
+                               dylib = realloc(dylib, (ndylib+32)*sizeof dylib[0]);
+                               if(dylib == nil) {
+                                       diag("out of memory");
+                                       errorexit();
+                               }
+                       }
+                       dylib[ndylib++] = s->dynimplib;
+               }
+       }
+       free(impsym);
+
        /*
         * list of symbol table indexes.
         * we don't take advantage of the opportunity
         * to order the symbol table differently from
         * this list, so it is boring: 0 1 2 3 4 ...
         */
-       for(x=0; x<nsym; x++) {
+       for(x=0; x<nexpsym+nimpsym; x++) {
                dat = grow(&linkdata, &nlinkdata, &mlinkdata, 4);
                dat[0] = x;
                dat[1] = x>>8;
@@ -331,16 +393,42 @@ domacho(void)
                dat[3] = x>>24;
        }
 
-       dynptrsize = nsym*ptrsize;
+       dynptrsize = (nexpsym+nimpsym) * ptrsize;
 }
 
 vlong
 domacholink(void)
 {
+       int i;
+       uchar *p;
+       Sym *s;
+       uint64 val;
+
        linkoff = 0;
        if(nlinkdata > 0) {
                linkoff = rnd(HEADR+textsize, INITRND) + rnd(datsize, INITRND);
                seek(cout, linkoff, 0);
+
+               for(i = 0; i<nexpsym; ++i) {
+                       s = expsym[i].s;
+                       val = s->value;
+                       if(s->type == SUNDEF)
+                               diag("export of undefined symbol %s", s->name);
+                       if (s->type != STEXT)
+                               val += INITDAT;
+                       p = linkdata+expsym[i].off;
+                       p[0] = val;
+                       p[1] = val >> 8;
+                       p[2] = val >> 16;
+                       p[3] = val >> 24;
+                       if (macho64) {
+                               p[4] = val >> 32;
+                               p[5] = val >> 40;
+                               p[6] = val >> 48;
+                               p[7] = val >> 56;
+                       }
+               }
+
                write(cout, linkdata, nlinkdata);
                write(cout, strtab, nstrtab);
        }
@@ -476,9 +564,9 @@ asmbmacho(vlong symdatva, vlong symo)
                ml->data[0] = 0;        /* ilocalsym */
                ml->data[1] = 0;        /* nlocalsym */
                ml->data[2] = 0;        /* iextdefsym */
-               ml->data[3] = 0;        /* nextdefsym */
-               ml->data[4] = 0;        /* iundefsym */
-               ml->data[5] = nsym;     /* nundefsym */
+               ml->data[3] = nexpsym;  /* nextdefsym */
+               ml->data[4] = nexpsym;  /* iundefsym */
+               ml->data[5] = nimpsym;  /* nundefsym */
                ml->data[6] = 0;        /* tocoffset */
                ml->data[7] = 0;        /* ntoc */
                ml->data[8] = 0;        /* modtaboff */