Kernel/LibC: Implement readlink and readlinkat

This commit is contained in:
Bananymous 2023-11-11 23:16:52 +02:00
parent 381cfdad77
commit c084ce8b01
5 changed files with 62 additions and 0 deletions

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@ -101,6 +101,9 @@ namespace Kernel
BAN::ErrorOr<long> sys_create(const char*, mode_t); BAN::ErrorOr<long> sys_create(const char*, mode_t);
BAN::ErrorOr<long> sys_create_dir(const char*, mode_t); BAN::ErrorOr<long> sys_create_dir(const char*, mode_t);
BAN::ErrorOr<long> sys_unlink(const char*); BAN::ErrorOr<long> sys_unlink(const char*);
BAN::ErrorOr<long> readlink_impl(BAN::StringView absolute_path, char* buffer, size_t bufsize);
BAN::ErrorOr<long> sys_readlink(const char* path, char* buffer, size_t bufsize);
BAN::ErrorOr<long> sys_readlinkat(int fd, const char* path, char* buffer, size_t bufsize);
BAN::ErrorOr<long> sys_chmod(const char*, mode_t); BAN::ErrorOr<long> sys_chmod(const char*, mode_t);

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@ -782,6 +782,47 @@ namespace Kernel
return 0; return 0;
} }
BAN::ErrorOr<long> Process::readlink_impl(BAN::StringView absolute_path, char* buffer, size_t bufsize)
{
auto inode = TRY(VirtualFileSystem::get().file_from_absolute_path(m_credentials, absolute_path, O_NOFOLLOW | O_RDONLY)).inode;
// FIXME: no allocation needed
auto link_target = TRY(inode->link_target());
size_t byte_count = BAN::Math::min<size_t>(link_target.size(), bufsize);
memcpy(buffer, link_target.data(), byte_count);
return byte_count;
}
BAN::ErrorOr<long> Process::sys_readlink(const char* path, char* buffer, size_t bufsize)
{
LockGuard _(m_lock);
validate_string_access(path);
validate_pointer_access(buffer, bufsize);
auto absolute_path = TRY(absolute_path_of(path));
return readlink_impl(absolute_path.sv(), buffer, bufsize);
}
BAN::ErrorOr<long> Process::sys_readlinkat(int fd, const char* path, char* buffer, size_t bufsize)
{
LockGuard _(m_lock);
validate_string_access(path);
validate_pointer_access(buffer, bufsize);
// FIXME: handle O_SEARCH in fd
auto parent_path = TRY(m_open_file_descriptors.path_of(fd));
BAN::String absolute_path;
TRY(absolute_path.append(parent_path));
TRY(absolute_path.push_back('/'));
TRY(absolute_path.append(path));
return readlink_impl(absolute_path.sv(), buffer, bufsize);
}
BAN::ErrorOr<long> Process::sys_chmod(const char* path, mode_t mode) BAN::ErrorOr<long> Process::sys_chmod(const char* path, mode_t mode)
{ {
if (mode & S_IFMASK) if (mode & S_IFMASK)

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@ -211,6 +211,12 @@ namespace Kernel
case SYS_UNLINK: case SYS_UNLINK:
ret = Process::current().sys_unlink((const char*)arg1); ret = Process::current().sys_unlink((const char*)arg1);
break; break;
case SYS_READLINK:
ret = Process::current().sys_readlink((const char*)arg1, (char*)arg2, (size_t)arg3);
break;
case SYS_READLINKAT:
ret = Process::current().sys_readlinkat((int)arg1, (const char*)arg2, (char*)arg3, (size_t)arg4);
break;
default: default:
dwarnln("Unknown syscall {}", syscall); dwarnln("Unknown syscall {}", syscall);
break; break;

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@ -59,6 +59,8 @@ __BEGIN_DECLS
#define SYS_CREATE 56 // creat, mkfifo #define SYS_CREATE 56 // creat, mkfifo
#define SYS_CREATE_DIR 57 // mkdir #define SYS_CREATE_DIR 57 // mkdir
#define SYS_UNLINK 58 #define SYS_UNLINK 58
#define SYS_READLINK 59
#define SYS_READLINKAT 60
__END_DECLS __END_DECLS

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@ -78,6 +78,16 @@ ssize_t write(int fildes, const void* buf, size_t nbyte)
return syscall(SYS_WRITE, fildes, buf, nbyte); return syscall(SYS_WRITE, fildes, buf, nbyte);
} }
ssize_t readlink(const char* __restrict path, char* __restrict buf, size_t bufsize)
{
return syscall(SYS_READLINK, path, buf, bufsize);
}
ssize_t readlinkat(int fd, const char* __restrict path, char* __restrict buf, size_t bufsize)
{
return syscall(SYS_READLINKAT, fd, path, buf, bufsize);
}
int dup(int fildes) int dup(int fildes)
{ {
return syscall(SYS_DUP, fildes); return syscall(SYS_DUP, fildes);