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output/coff: Possibility to define the associated comdat sections in any order

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Signed-off-by: "Glücksmann, Igor" <igor.glucksmann@avast.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
This commit is contained in:
Igor Glucksmann 2021-04-07 13:58:04 +02:00 committed by Cyrill Gorcunov
parent ed2c609976
commit 27e17c913c
1 changed files with 118 additions and 42 deletions
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160
output/outcoff.c
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@ -186,6 +186,8 @@ static void coff_write_relocs(struct coff_Section *);
static void coff_write_symbols(void);
static void coff_defcomdatname(char *name, int32_t segment);
#define COMDAT_PLACEHOLDER_NAME ".tmpcmdt"
static void coff_win32_init(void)
{
win32 = true;
@ -288,6 +290,31 @@ int coff_make_section(char *name, uint32_t flags)
return coff_nsects - 1;
}
/*
* Update the name and flags of an existing section
*/
static void coff_update_section(int section, char *name, uint32_t flags)
{
struct coff_Section *s = coff_sects[section];
size_t namelen = strlen(name);
if (namelen > 8) {
if (win32 || win64) {
s->namepos = strslen + 4;
saa_wbytes(coff_strs, name, namelen + 1);
strslen += namelen + 1;
} else {
namelen = 8;
}
}
nasm_free(s->name);
s->name = nasm_malloc(namelen + 1);
strncpy(s->name, name, namelen);
s->name[namelen] = '\0';
s->flags = flags;
}
/*
* Convert an alignment value to the corresponding flags.
* An alignment value of 0 means no flags should be set.
@ -306,12 +333,38 @@ static inline unsigned int coff_alignment(uint32_t flags)
return (1U << ((flags & IMAGE_SCN_ALIGN_MASK) >> 20)) >> 1;
}
/*
* Get the default section flags (based on section name)
*/
static uint32_t coff_section_flags(char *name, uint32_t flags)
{
if (!flags) {
flags = TEXT_FLAGS;
if (!strcmp(name, ".data")) {
flags = DATA_FLAGS;
} else if (!strcmp(name, ".rdata")) {
flags = RDATA_FLAGS;
} else if (!strcmp(name, ".bss")) {
flags = BSS_FLAGS;
} else if (win64) {
if (!strcmp(name, ".pdata"))
flags = PDATA_FLAGS;
else if (!strcmp(name, ".xdata"))
flags = XDATA_FLAGS;
}
}
return flags;
}
static int32_t coff_section_names(char *name, int *bits)
{
char *p, *comdat_name;
uint32_t flags, align_flags;
int i, j;
int8_t comdat_selection;
int32_t comdat_associated;
/*
* Set default bits.
@ -336,7 +389,7 @@ static int32_t coff_section_names(char *name, int *bits)
name[8] = '\0';
}
}
flags = align_flags = comdat_selection = 0;
flags = align_flags = comdat_selection = comdat_associated = 0;
comdat_name = NULL;
while (*p && nasm_isspace(*p))
@ -400,7 +453,7 @@ static int32_t coff_section_names(char *name, int *bits)
comdat_selection = strtoul(q + 7, &q, 10);
if (!comdat_selection)
nasm_nonfatal("invalid argument to `comdat'");
else if (*q != ':')
else if (*q != ':' || q[1] == '\0')
nasm_nonfatal("missing name in `comdat'");
else {
comdat_name = q + 1;
@ -429,48 +482,61 @@ static int32_t coff_section_names(char *name, int *bits)
}
}
}
if (i == coff_nsects) {
if (!flags) {
flags = TEXT_FLAGS;
if (!strcmp(name, ".data")) {
flags = DATA_FLAGS;
} else if (!strcmp(name, ".rdata")) {
flags = RDATA_FLAGS;
} else if (!strcmp(name, ".bss")) {
flags = BSS_FLAGS;
} else if (win64) {
if (!strcmp(name, ".pdata"))
flags = PDATA_FLAGS;
else if (!strcmp(name, ".xdata"))
flags = XDATA_FLAGS;
}
else if (comdat_name && coff_sects[i]->comdat_name &&
!coff_sects[i]->comdat_selection &&
!strcmp(comdat_name, coff_sects[i]->comdat_name) &&
comdat_selection != IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
/*
* This seems to be a "placeholder section" we've created before
* to be the associate of a previous comdat section.
* We'll just update the name and flags with the real ones now.
*/
flags = coff_section_flags(name, flags);
coff_update_section(i, name, flags | IMAGE_SCN_LNK_COMDAT);
coff_sects[i]->comdat_selection = comdat_selection;
break;
}
if (comdat_name)
if (i == coff_nsects) {
flags = coff_section_flags(name, flags);
if (comdat_name) {
flags |= IMAGE_SCN_LNK_COMDAT;
if (comdat_selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
/*
* Find an existing section with given comdat name
*/
for (j = 0; j < coff_nsects; j++)
if (coff_sects[j]->comdat_name &&
!strcmp(coff_sects[j]->comdat_name, comdat_name))
break;
if (j == coff_nsects) {
/*
* The associated section doesn't exist (yet)
* Even though the specs don't enforce a particular order,
* VS (2019) linker doesn't accept .obj files where the
* target section is a later one (than the one with sel==5)
*
* So let's insert another section now (a placeholder),
* hoping it will be turned into the target section later.
*/
j = coff_make_section(COMDAT_PLACEHOLDER_NAME, TEXT_FLAGS);
coff_sects[j]->comdat_name = nasm_strdup(comdat_name);
}
comdat_associated = j + 1;
}
}
i = coff_make_section(name, flags);
coff_sects[i]->align_flags = align_flags;
if (comdat_name) {
coff_sects[i]->comdat_selection = comdat_selection;
coff_sects[i]->comdat_name = strdup(comdat_name);
if (comdat_selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
/*
* Find a previous section with given comdat name
*/
for (j = 0; j < coff_nsects - 1; j++)
if (coff_sects[j]->comdat_name &&
!strcmp(coff_sects[j]->comdat_name, comdat_name))
break;
if (j < coff_nsects - 1) {
coff_sects[i]->comdat_associated = j + 1;
}
else
nasm_nonfatal("unknown `comdat' associative");
}
coff_sects[i]->comdat_associated = comdat_associated;
coff_sects[i]->comdat_name = nasm_strdup(comdat_name);
}
} else {
if (flags) {
@ -1000,15 +1066,25 @@ static void coff_write(void)
}
/*
* Check if all comdat sections have their comdat symbol
* If not, define it
* Check all comdat sections
*/
for (i = 0; i < coff_nsects; i++) {
if (coff_sects[i]->comdat_name && !coff_sects[i]->comdat_symbol &&
coff_sects[i]->comdat_selection != IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
coff_defcomdatname(coff_sects[i]->comdat_name, coff_sects[i]->index);
for (i = 0; i < coff_nsects; i++)
if (coff_sects[i]->comdat_name) {
if (!coff_sects[i]->comdat_symbol &&
coff_sects[i]->comdat_selection != IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
/*
* This section doesn't have its comdat symbol defined; do it
*/
coff_defcomdatname(coff_sects[i]->comdat_name, coff_sects[i]->index);
}
if (!coff_sects[i]->comdat_selection) {
/*
* This is a placeholder section that wasn't properly defined
*/
nasm_nonfatal("`comdat' associate with symbol `%s` wasn't defined",
coff_sects[i]->comdat_name);
}
}
}
/*
* Work out how big the file will get.