ref: dc1712922b142c0f4199ccf8bd60d45bf43bf304
parent: b1b925a092fd55df9eaf6a05fe5f03a4ec4f8378
author: Roberto E. Vargas Caballero <k0ga@shike2.com>
date: Tue Feb 26 03:12:48 EST 2019
[ld] Rework how sections are loaded
--- a/src/cmd/ld.c
+++ b/src/cmd/ld.c
@@ -31,7 +31,9 @@
struct section {char *name;
- unsigned long long size;
+ unsigned long long size, offset;
+ unsigned flags;
+ int type;
FILE *fp;
Section *next;
};
@@ -202,51 +204,101 @@
}
static void
-newsect(Objsect *secp, FILE *fp)
+copy(FILE *to, FILE *from, long pad, long nbytes)
{int c;
- unsigned long long align, size;
- Section *sp;
- for (sp = sections; sp; sp = sp->next) {- if (!strcmp(sp->name, secp->name))
- break;
+ while (pad--)
+ putc(0, to);
+
+ while (nbytes-- && (c = getc(from)) != EOF)
+ putc(c, to);
+
+ if (c == EOF) {+ error("section truncated");+ exit(EXIT_FAILURE);
}
- if (!sp) {- size_t len = strlen(secp->name) + 1;
- char * s = malloc(len);
- FILE *fp = tmpfile();
+ if (ferror(to) || ferror(from)) {+ error(errstr());
+ exit(EXIT_FAILURE);
+ }
+}
- sp = malloc(sizeof(*sp));
- if (!s || !sp || !fp)
- goto err;
+static Section *
+findsect(Objsect *secp)
+{+ size_t len;
+ char *s;
+ FILE *fp;
+ Section *sp, *lastp;
- sp->name = memcpy(s, secp->name, len);
- sp->size = 0;
- sp->fp = fp;
- sp->next = sections;
+ for (lastp = sp = sections; sp; lastp = sp, sp = sp->next) {+ if (!strcmp(sp->name, secp->name))
+ return sp;
+ }
- if (!sections)
- sections = sp;
+ len = strlen(secp->name) + 1;
+ s = malloc(len);
+ fp = tmpfile();
+
+ sp = malloc(sizeof(*sp));
+ if (!s || !sp || !fp) {+ error(errstr());
+ exit(EXIT_FAILURE);
}
- align = secp->align-1;
- size = (sp->size + align) & ~align;
+ if (lastp) {+ lastp->next = sp;
+ } else {+ sections = sp;
+ sp->next = NULL;
+ }
- for (; secp->size < size; secp->size++)
- putc(0, sp->fp);
+ sp->name = memcpy(s, secp->name, len);
+ sp->offset = sp->size = 0;
+ sp->fp = fp;
+ sp->flags = secp->flags;
+ sp->type = secp->type;
- fseek(fp, secp->offset, SEEK_SET);
- while ((c = getc(fp)) != EOF)
- putc(c, sp->fp);
- fflush(sp->fp);
+ return sp;
+}
- if (!ferror(fp) && !ferror(sp->fp))
- return;
+extern int objpos(Obj *obj, FILE *fp, long pos);
-err:
- error(errstr());
+static void
+newsect(Objsect *secp, Obj *obj, FILE *fp)
+{+ unsigned long long align, size, pad, off;
+ Section *sp;
+
+ sp = findsect(secp);
+
+ align = secp->align - 1;
+ pad = (sp->size+align) & ~align;
+
+ if (sp->size > ULLONG_MAX - pad)
+ goto overflow;
+ off = sp->size += pad;
+
+ if (sp->size > ULLONG_MAX - secp->size)
+ goto overflow;
+ sp->size += secp->size;
+
+ objpos(obj, fp, secp->offset);
+ copy(sp->fp, fp, pad, secp->size);
+
+ /*
+ * and now update the offset to relect the offset
+ * in the output file
+ */
+ secp->offset = off;
+
+ return;
+
+overflow:
+ error("section overflow");+ exit(EXIT_FAILURE);
}
static void
@@ -262,9 +314,6 @@
return;
}
- if (objsect(obj) < 0 || objsyms(obj) < 0)
- goto err1;
-
lst->obj = obj;
lst->next = NULL;
@@ -277,13 +326,7 @@
newsym(sym, obj);
for (secp = obj->secs; secp; secp = secp->next)
- newsect(secp, fp);
-
- return;
-
-err1:
- free(lst);
- error("out of memory");+ newsect(secp, obj, fp);
}
static void
@@ -301,7 +344,7 @@
bintype = type;
} else if (bintype != type) { error("not compatible object file");- return;
+ goto delete;
}
bintype = type;
@@ -310,19 +353,29 @@
goto delete;
}
- if (inlib) {- p = &refhead;
- for (sym = p->next; sym != p; sym = sym->next) {- if (objlookup(obj, sym->name, 0))
- break;
- }
- if (sym == p)
- goto delete;
+ if (objsyms(obj) < 0 || objsect(obj) < 0) {+ error("object file corrupted");+ goto delete;
}
- loadobj(obj, fp);
- return;
+ if (!inlib) {+ loadobj(obj, fp);
+ return;
+ }
+ /*
+ * we are in a library without index, so we have to check
+ * if it defines some symbol that is undefined and only
+ * in that case we have to load the object
+ */
+ p = &refhead;
+ for (sym = p->next; sym != p; sym = sym->next) {+ if (objlookup(obj, sym->name, 0)) {+ loadobj(obj, fp);
+ return;
+ }
+ }
+
delete:
objdel(obj);
return;
@@ -341,7 +394,8 @@
return;
}
- for (loaded = 1; moreundef() && loaded; ) {+ loaded = 1;
+ while (moreundef() && loaded) {loaded = 0;
for (dp = def; dp; dp = dp->next) {sym = lookup(dp->name, NOINSTALL);
@@ -377,8 +431,6 @@
int t;
int *nmemb = data;
- membname = data;
-
if (bintype == -1) { error("an object file is needed before any library");return 0;
@@ -392,6 +444,7 @@
}
}
+ membname = name;
if ((t = objtype(fp, NULL)) == -1)
return 1;
@@ -401,6 +454,7 @@
}
newobject(fp, t, INLIB);
+ membname = NULL;
return 1;
}
@@ -459,6 +513,19 @@
}
static void
+listundef(void)
+{+ Symbol *sym, *p;
+
+ p = &refhead;
+ for (sym = p->next; sym != p; sym = sym->next) {+ fprintf(stderr,
+ "ld: symbol '%s' not defined\n",
+ sym->name);
+ }
+}
+
+static void
pass1(int argc, char *argv[])
{int t;
@@ -480,21 +547,60 @@
}
if (moreundef()) {- Symbol *sym, *p;
-
- p = &refhead;
- for (sym = p->next; sym != p; sym = sym->next) {- fprintf(stderr,
- "ld: symbol '%s' not defined\n",
- sym->name);
- }
+ listundef();
exit(EXIT_FAILURE);
}
}
+/*
+ * default memory layout:
+ * -text
+ * -data
+ * -bss
+ */
static void
pass2(int argc, char *argv[])
{+ FILE *fp;
+ Section *sp;
+ long off;
+ unsigned long long addr;
+
+ if ((fp = fopen("binary", "wb")) == NULL) {+ perror("opening output");+ exit(EXIT_FAILURE);
+ }
+
+ addr = 0x100;
+ for (sp = sections; sp; sp = sp->next) {+ fprintf(stderr, "1st - %c\n", sp->type);
+ if (sp->type != 'T')
+ continue;
+ rewind(sp->fp);
+ copy(fp, sp->fp, 0, sp->size);
+ addr += sp->size;
+ fclose(sp->fp);
+ }
+
+ addr = addr+3 & ~3;
+ for (sp = sections; sp; sp = sp->next) {+ fprintf(stderr, "2nd - %c\n", sp->type);
+ if (sp->type != 'D')
+ continue;
+ rewind(sp->fp);
+ copy(fp, sp->fp, 0, sp->size);
+ addr += sp->size;
+ fclose(sp->fp);
+ }
+
+ addr = addr+3 & ~3;
+ for (sp = sections; sp; sp = sp->next) {+ fprintf(stderr, "3rd - %c\n", sp->type);
+ if (sp->type != 'B')
+ continue;
+ addr += sp->size;
+ fclose(sp->fp);
+ }
}
static void