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LibC: Implement ungetc() 

I didn't really test this, but I think this implementation does what it
needs to :)
This commit is contained in:
Bananymous 2024-08-12 19:14:55 +03:00
parent 39be57424c
commit 25a47f0df3
1 changed files with 29 additions and 4 deletions
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33
userspace/libraries/LibC/stdio.cpp
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@ -23,6 +23,8 @@ struct FILE
int pid { -1 }; int pid { -1 };
int unget_char { EOF };
unsigned char inline_buffer_storage[BUFSIZ] {}; unsigned char inline_buffer_storage[BUFSIZ] {};
unsigned char* buffer = inline_buffer_storage; unsigned char* buffer = inline_buffer_storage;
uint32_t buffer_size = BUFSIZ; uint32_t buffer_size = BUFSIZ;
@ -149,6 +151,8 @@ int fflush(FILE* file)
ScopeLock _(file); ScopeLock _(file);
file->unget_char = EOF;
if (file->buffer_index == 0) if (file->buffer_index == 0)
return 0; return 0;
@ -282,9 +286,16 @@ size_t fread(void* buffer, size_t size, size_t nitems, FILE* file)
size_t target = size * nitems; size_t target = size * nitems;
size_t nread = 0; size_t nread = 0;
if (file->unget_char != EOF)
{
*static_cast<unsigned char*>(buffer) = file->unget_char;
file->unget_char = EOF;
nread++;
}
while (nread < target) while (nread < target)
{ {
ssize_t ret = syscall(SYS_READ, file->fd, (uint8_t*)buffer + nread, target - nread); ssize_t ret = syscall(SYS_READ, file->fd, static_cast<unsigned char*>(buffer) + nread, target - nread);
if (ret < 0) if (ret < 0)
file->error = true; file->error = true;
@ -350,6 +361,7 @@ int fseek(FILE* file, long offset, int whence)
int fseeko(FILE* file, off_t offset, int whence) int fseeko(FILE* file, off_t offset, int whence)
{ {
ScopeLock _(file); ScopeLock _(file);
file->unget_char = EOF;
long ret = syscall(SYS_SEEK, file->fd, offset, whence); long ret = syscall(SYS_SEEK, file->fd, offset, whence);
if (ret < 0) if (ret < 0)
return -1; return -1;
@ -373,7 +385,7 @@ off_t ftello(FILE* file)
long ret = syscall(SYS_TELL, file->fd); long ret = syscall(SYS_TELL, file->fd);
if (ret < 0) if (ret < 0)
return -1; return -1;
return ret; return ret - (file->unget_char != EOF);
} }
int ftrylockfile(FILE*) int ftrylockfile(FILE*)
@ -413,6 +425,13 @@ int getc_unlocked(FILE* file)
if (file->eof) if (file->eof)
return EOF; return EOF;
if (file->unget_char != EOF)
{
int ch = file->unget_char;
file->unget_char = EOF;
return (unsigned char)ch;
}
unsigned char c; unsigned char c;
long ret = syscall(SYS_READ, file->fd, &c, 1); long ret = syscall(SYS_READ, file->fd, &c, 1);
@ -749,8 +768,14 @@ char* tmpnam(char* storage)
int ungetc(int c, FILE* stream) int ungetc(int c, FILE* stream)
{ {
dwarnln("FIXME: ungetc({}, {})", c, stream); if (c == EOF)
ASSERT_NOT_REACHED(); return EOF;
ScopeLock _(stream);
if (stream->unget_char != EOF)
return EOF;
stream->unget_char = c;
stream->eof = false;
return (unsigned char)c;
} }
int vfprintf(FILE* file, const char* format, va_list arguments) int vfprintf(FILE* file, const char* format, va_list arguments)