97 lines
2.9 KiB
C
97 lines
2.9 KiB
C
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#include <stdint.h>
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#include <stddef.h>
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typedef int _PDCLIB_fd_t;
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static inline int32_t inline_syscall(uint32_t num, uint32_t arg1, uint32_t arg2, uint32_t arg3) {
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int32_t ret;
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asm volatile (
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"int $0x80"
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: "=a" (ret)
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: "a" (num), "b" (arg1), "c" (arg2), "d" (arg3)
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: "memory"
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);
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return ret;
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}
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void _PDCLIB_exit(int status) {
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inline_syscall(1, (uint32_t)status, 0, 0);
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while(1); // Halt if exit fails to yield
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}
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int _PDCLIB_read(_PDCLIB_fd_t fd, void *buf, size_t count) {
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return inline_syscall(3, (uint32_t)fd, (uint32_t)buf, (uint32_t)count);
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}
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// 3. sys_write (eax = 4)
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int _PDCLIB_write(_PDCLIB_fd_t fd, const void *buf, size_t count) {
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return inline_syscall(4, (uint32_t)fd, (uint32_t)buf, (uint32_t)count);
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}
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_PDCLIB_fd_t _PDCLIB_open(const char *filename, unsigned int mode) {
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_PDCLIB_fd_t fd;
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fd = inline_syscall(5, (uint32_t)filename, (uint32_t)mode, 0);
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return fd;
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}
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int _PDCLIB_close(_PDCLIB_fd_t fd) {
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return inline_syscall(6, (uint32_t)fd, 0, 0);
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}
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void * _PDCLIB_allocpages(size_t n) {
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// n is the number of PAGES PDCLib wants (usually 4096 bytes per page)
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size_t bytes_requested = n * 4096;
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// Call your sys_brk with 0 to find the current break address
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uint32_t current_break = inline_syscall(12, 0, 0, 0);
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// Request the new break point
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uint32_t new_break = current_break + bytes_requested;
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uint32_t result = inline_syscall(12, new_break, 0, 0);
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if (result == 0) {
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return (void *)current_break; // Return the start of the newly allocated region
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}
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return NULL; // Allocation failed
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}
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int _PDCLIB_remove(const char *filename) { return -1; }
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int _PDCLIB_rename(const char *old, const char *new) { return -1; }
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long _PDCLIB_lseek(_PDCLIB_fd_t fd, long offset, int whence) { return -1; }
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int open(const char *pathname, int flags, ...) {
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// Wrap to your internal _PDCLIB_open or inline_syscall directly
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_PDCLIB_fd_t fd = _PDCLIB_open(pathname, (unsigned int)flags);
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return fd;
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}
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int read(int fd, void *buf, size_t count) {
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_PDCLIB_fd_t file_desc = fd;
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return _PDCLIB_read(file_desc, buf, count);
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}
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int write(int fd, const void *buf, size_t count) {
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return _PDCLIB_write(fd, buf, count);
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}
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int close(int fd) {
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_PDCLIB_fd_t file_desc = fd;
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return _PDCLIB_close(file_desc);
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}
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void _exit(int status) {
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_PDCLIB_exit(status);
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}
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void * sbrk(intptr_t increment) {
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// If increment is 0, dlmalloc is querying the current boundary.
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// For a simple implementation, let's look up memory by pages.
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if (increment == 0) {
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return _PDCLIB_allocpages(0);
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}
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// Convert bytes requested by sbrk into page increments (4KB blocks)
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// You can also change your syscall wrapper to use regular byte increments
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size_t pages_needed = ((size_t)increment + 4095) / 4096;
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return _PDCLIB_allocpages(pages_needed);
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}
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