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io: rework how we set SDL_IOStream status.

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This now relies on the implementation to set these flags on short reads/writes
instead of the higher level checking if SDL_SetError() was called.

Additionally (and crucially), this now sets ERROR or EOF on all short reads,
across all backends, not just when we get a zero-byte return value.

Fixes #13720.
This commit is contained in:
Ryan C. Gordon
2025-09-05 10:12:42 -04:00
parent 129c97f610
commit b8197a2291
3 changed files with 66 additions and 41 deletions
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12
include/SDL3/SDL_iostream.h
View File

@@ -111,7 +111,7 @@ typedef struct SDL_IOStreamInterface
/**
* Read up to `size` bytes from the data stream to the area pointed
* at by `ptr`.
* at by `ptr`. `size` will always be > 0.
*
* On an incomplete read, you should set `*status` to a value from the
* SDL_IOStatus enum. You do not have to explicitly set this on
@@ -123,7 +123,7 @@ typedef struct SDL_IOStreamInterface
/**
* Write exactly `size` bytes from the area pointed at by `ptr`
* to data stream.
* to data stream. `size` will always be > 0.
*
* On an incomplete write, you should set `*status` to a value from the
* SDL_IOStatus enum. You do not have to explicitly set this on
@@ -580,6 +580,10 @@ extern SDL_DECLSPEC Sint64 SDLCALL SDL_TellIO(SDL_IOStream *context);
* the stream is not at EOF, SDL_GetIOStatus() will return a different error
* value and SDL_GetError() will offer a human-readable message.
*
* A request for zero bytes on a valid stream will return zero immediately
* without accessing the stream, so the stream status (EOF, err, etc) will
* not change.
*
* \param context a pointer to an SDL_IOStream structure.
* \param ptr a pointer to a buffer to read data into.
* \param size the number of bytes to read from the data source.
@@ -609,6 +613,10 @@ extern SDL_DECLSPEC size_t SDLCALL SDL_ReadIO(SDL_IOStream *context, void *ptr,
* recoverable, such as a non-blocking write that can simply be retried later,
* or a fatal error.
*
* A request for zero bytes on a valid stream will return zero immediately
* without accessing the stream, so the stream status (EOF, err, etc) will
* not change.
*
* \param context a pointer to an SDL_IOStream structure.
* \param ptr a pointer to a buffer containing data to write.
* \param size the number of bytes to write.

4
src/core/android/SDL_android.c
View File

@@ -1827,7 +1827,10 @@ size_t Android_JNI_FileRead(void *userdata, void *buffer, size_t size, SDL_IOSta
const int bytes = AAsset_read((AAsset *)userdata, buffer, size);
if (bytes < 0) {
SDL_SetError("AAsset_read() failed");
*status = SDL_IO_STATUS_ERROR;
return 0;
} else if (bytes < size) {
*status = SDL_IO_STATUS_EOF;
}
return (size_t)bytes;
}
@@ -1835,6 +1838,7 @@ size_t Android_JNI_FileRead(void *userdata, void *buffer, size_t size, SDL_IOSta
size_t Android_JNI_FileWrite(void *userdata, const void *buffer, size_t size, SDL_IOStatus *status)
{
SDL_SetError("Cannot write to Android package filesystem");
*status = SDL_IO_STATUS_ERROR;
return 0;
}

91
src/io/SDL_iostream.c
View File

@@ -220,15 +220,17 @@ static size_t SDLCALL windows_file_read(void *userdata, void *ptr, size_t size,
switch (error) {
case ERROR_BROKEN_PIPE:
case ERROR_HANDLE_EOF:
*status = SDL_IO_STATUS_EOF;
break;
case ERROR_NO_DATA:
*status = SDL_IO_STATUS_NOT_READY;
break;
default:
*status = SDL_IO_STATUS_ERROR;
WIN_SetError("Error reading from datastream");
break;
}
return 0;
return 0; // !!! FIXME: this should return the bytes read from any readahead we finished out before this (the `iodata->left > 0` code above). In that case, fail on the next read.
}
read_ahead = SDL_min(total_need, bytes);
SDL_memcpy(ptr, iodata->data, read_ahead);
@@ -241,15 +243,17 @@ static size_t SDLCALL windows_file_read(void *userdata, void *ptr, size_t size,
switch (error) {
case ERROR_BROKEN_PIPE:
case ERROR_HANDLE_EOF:
*status = SDL_IO_STATUS_EOF;
break;
case ERROR_NO_DATA:
*status = SDL_IO_STATUS_NOT_READY;
break;
default:
*status = SDL_IO_STATUS_ERROR;
WIN_SetError("Error reading from datastream");
break;
}
return 0;
return 0; // !!! FIXME: this should return the bytes read from any readahead we finished out before this (the `iodata->left > 0` code above). In that case, fail on the next read.
}
total_read += bytes;
}
@@ -263,6 +267,7 @@ static size_t SDLCALL windows_file_write(void *userdata, const void *ptr, size_t
if (iodata->left) {
if (!SetFilePointer(iodata->h, -(LONG)iodata->left, NULL, FILE_CURRENT)) {
*status = SDL_IO_STATUS_ERROR;
WIN_SetError("Error seeking in datastream");
return 0;
}
@@ -274,16 +279,17 @@ static size_t SDLCALL windows_file_write(void *userdata, const void *ptr, size_t
LARGE_INTEGER windowsoffset;
windowsoffset.QuadPart = 0;
if (!SetFilePointerEx(iodata->h, windowsoffset, &windowsoffset, FILE_END)) {
*status = SDL_IO_STATUS_ERROR;
WIN_SetError("Error seeking in datastream");
return 0;
}
}
if (!WriteFile(iodata->h, ptr, (DWORD)size, &bytes, NULL)) {
*status = SDL_IO_STATUS_ERROR;
WIN_SetError("Error writing to datastream");
return 0;
}
if (bytes == 0 && size > 0) {
} else if (bytes == 0 && size > 0) {
*status = SDL_IO_STATUS_NOT_READY;
}
return bytes;
@@ -421,9 +427,12 @@ static size_t SDLCALL fd_read(void *userdata, void *ptr, size_t size, SDL_IOStat
if (errno == EAGAIN) {
*status = SDL_IO_STATUS_NOT_READY;
} else {
*status = SDL_IO_STATUS_ERROR;
SDL_SetError("Error reading from datastream: %s", strerror(errno));
}
bytes = 0;
} else if (bytes < size) {
*status = SDL_IO_STATUS_EOF;
}
return (size_t)bytes;
}
@@ -440,6 +449,7 @@ static size_t SDLCALL fd_write(void *userdata, const void *ptr, size_t size, SDL
if (errno == EAGAIN) {
*status = SDL_IO_STATUS_NOT_READY;
} else {
*status = SDL_IO_STATUS_ERROR;
SDL_SetError("Error writing to datastream: %s", strerror(errno));
}
bytes = 0;
@@ -606,12 +616,18 @@ static size_t SDLCALL stdio_read(void *userdata, void *ptr, size_t size, SDL_IOS
{
IOStreamStdioData *iodata = (IOStreamStdioData *) userdata;
const size_t bytes = fread(ptr, 1, size, iodata->fp);
if (bytes == 0 && ferror(iodata->fp)) {
if (errno == EAGAIN) {
*status = SDL_IO_STATUS_NOT_READY;
clearerr(iodata->fp);
if (bytes < size) {
if (ferror(iodata->fp)) {
if (errno == EAGAIN) {
*status = SDL_IO_STATUS_NOT_READY;
clearerr(iodata->fp);
} else {
*status = SDL_IO_STATUS_ERROR;
SDL_SetError("Error reading from datastream: %s", strerror(errno));
}
} else {
SDL_SetError("Error reading from datastream: %s", strerror(errno));
SDL_assert(feof(iodata->fp));
*status = SDL_IO_STATUS_EOF;
}
}
return bytes;
@@ -626,6 +642,7 @@ static size_t SDLCALL stdio_write(void *userdata, const void *ptr, size_t size,
*status = SDL_IO_STATUS_NOT_READY;
clearerr(iodata->fp);
} else {
*status = SDL_IO_STATUS_ERROR;
SDL_SetError("Error writing to datastream: %s", strerror(errno));
}
}
@@ -769,13 +786,22 @@ static size_t mem_io(void *userdata, void *dst, const void *src, size_t size)
static size_t SDLCALL mem_read(void *userdata, void *ptr, size_t size, SDL_IOStatus *status)
{
IOStreamMemData *iodata = (IOStreamMemData *) userdata;
return mem_io(userdata, ptr, iodata->here, size);
const size_t retval = mem_io(userdata, ptr, iodata->here, size);
if ((retval < size) && (iodata->stop == iodata->here)) {
*status = SDL_IO_STATUS_EOF;
}
return retval;
}
static size_t SDLCALL mem_write(void *userdata, const void *ptr, size_t size, SDL_IOStatus *status)
{
IOStreamMemData *iodata = (IOStreamMemData *) userdata;
return mem_io(userdata, iodata->here, ptr, size);
const size_t retval = mem_io(userdata, iodata->here, ptr, size);
if ((retval < size) && (iodata->stop == iodata->here)) {
SDL_SetError("Memory buffer is full");
*status = SDL_IO_STATUS_ERROR;
}
return retval;
}
static bool SDLCALL mem_close(void *userdata)
@@ -1027,7 +1053,11 @@ static Sint64 SDLCALL dynamic_mem_seek(void *userdata, Sint64 offset, SDL_IOWhen
static size_t SDLCALL dynamic_mem_read(void *userdata, void *ptr, size_t size, SDL_IOStatus *status)
{
IOStreamDynamicMemData *iodata = (IOStreamDynamicMemData *) userdata;
return mem_io(&iodata->data, ptr, iodata->data.here, size);
const size_t retval = mem_io(&iodata->data, ptr, iodata->data.here, size);
if ((retval < size) && (iodata->data.stop == iodata->data.here)) {
*status = SDL_IO_STATUS_EOF;
}
return retval;
}
static bool dynamic_mem_realloc(IOStreamDynamicMemData *iodata, size_t size)
@@ -1060,12 +1090,15 @@ static size_t SDLCALL dynamic_mem_write(void *userdata, const void *ptr, size_t
if (size > (size_t)(iodata->data.stop - iodata->data.here)) {
if (size > (size_t)(iodata->end - iodata->data.here)) {
if (!dynamic_mem_realloc(iodata, size)) {
*status = SDL_IO_STATUS_ERROR;
return 0;
}
}
iodata->data.stop = iodata->data.here + size;
}
return mem_io(&iodata->data, iodata->data.here, ptr, size);
const size_t retval = mem_io(&iodata->data, iodata->data.here, ptr, size);
SDL_assert(retval == size); // we should have allocated enough to cover this!
return retval;
}
static bool SDLCALL dynamic_mem_close(void *userdata)
@@ -1333,8 +1366,6 @@ Sint64 SDL_TellIO(SDL_IOStream *context)
size_t SDL_ReadIO(SDL_IOStream *context, void *ptr, size_t size)
{
size_t bytes;
if (!context) {
SDL_InvalidParamError("context");
return 0;
@@ -1342,30 +1373,18 @@ size_t SDL_ReadIO(SDL_IOStream *context, void *ptr, size_t size)
context->status = SDL_IO_STATUS_WRITEONLY;
SDL_Unsupported();
return 0;
} else if (size == 0) {
return 0; // context->status doesn't change for this.
}
context->status = SDL_IO_STATUS_READY;
SDL_ClearError();
if (size == 0) {
return 0;
}
bytes = context->iface.read(context->userdata, ptr, size, &context->status);
if (bytes == 0 && context->status == SDL_IO_STATUS_READY) {
if (*SDL_GetError()) {
context->status = SDL_IO_STATUS_ERROR;
} else {
context->status = SDL_IO_STATUS_EOF;
}
}
return bytes;
return context->iface.read(context->userdata, ptr, size, &context->status);
}
size_t SDL_WriteIO(SDL_IOStream *context, const void *ptr, size_t size)
{
size_t bytes;
if (!context) {
SDL_InvalidParamError("context");
return 0;
@@ -1373,20 +1392,14 @@ size_t SDL_WriteIO(SDL_IOStream *context, const void *ptr, size_t size)
context->status = SDL_IO_STATUS_READONLY;
SDL_Unsupported();
return 0;
} else if (size == 0) {
return 0; // context->status doesn't change for this.
}
context->status = SDL_IO_STATUS_READY;
SDL_ClearError();
if (size == 0) {
return 0;
}
bytes = context->iface.write(context->userdata, ptr, size, &context->status);
if ((bytes == 0) && (context->status == SDL_IO_STATUS_READY)) {
context->status = SDL_IO_STATUS_ERROR;
}
return bytes;
return context->iface.write(context->userdata, ptr, size, &context->status);
}
size_t SDL_IOprintf(SDL_IOStream *context, SDL_PRINTF_FORMAT_STRING const char *fmt, ...)