kernel/ext2: Replace a manually allocated buffer with Buffer

This also lets us keep it empty unless it is used, in which case we resize it (if it wasn't already resized).

kernel/src/arch/x86_64/disk/ATA.cpp

@@ -6,6 +6,7 @@
 #include "fs/MBR.h"
 #include "memory/MemoryManager.h"
 #include <luna/Alignment.h>
+#include <luna/Buffer.h>
 #include <luna/CType.h>
 #include <luna/SafeArithmetic.h>
 #include <luna/Vector.h>
@@ -758,9 +759,7 @@ Result<u64> ATADevice::read(u8* buf, usize offset, usize size) const
 
     ScopedKMutexLock<100> lock(m_drive->channel()->lock());
 
-    // FIXME: Don't always allocate this if we don't need it.
+    Buffer temp;
-    auto* temp = (u8*)TRY(malloc_impl(block_size));
-    auto guard = make_scope_guard([temp] { free_impl(temp); });
 
     if (offset % block_size)
     {
@@ -769,8 +768,10 @@ Result<u64> ATADevice::read(u8* buf, usize offset, usize size) const
         // Maybe we don't even want enough to get to the next block?
         if (extra_size > size) extra_size = size;
 
-        TRY(m_drive->read_lba(offset / block_size, temp, 1));
+        TRY(temp.try_resize(block_size));
-        memcpy(buf, temp + (offset % block_size), extra_size);
+
+        TRY(m_drive->read_lba(offset / block_size, temp.data(), 1));
+        memcpy(buf, temp.data() + (offset % block_size), extra_size);
         offset += extra_size;
         size -= extra_size;
         buf += extra_size;
@@ -794,8 +795,9 @@ Result<u64> ATADevice::read(u8* buf, usize offset, usize size) const
 
     if (size)
     {
-        TRY(m_drive->read_lba(offset / block_size, temp, 1));
+        TRY(temp.try_resize(block_size));
-        memcpy(buf, temp, size);
+        TRY(m_drive->read_lba(offset / block_size, temp.data(), 1));
+        memcpy(buf, temp.data(), size);
     }
 
     return length;

kernel/src/fs/GPT.cpp

@@ -66,6 +66,9 @@ namespace GPT
     {
         header.checksum = 0;
 
-        return CRC32::checksum((u8*)&header, 0x5c);
+        CRC32 crc;
+        crc.append((u8*)&header, 0x5c);
+
+        return crc.digest();
     }
 }

kernel/src/fs/Pipe.cpp

@@ -44,7 +44,11 @@ Result<usize> Pipe::read(u8* buf, usize, usize length)
 
 Result<usize> Pipe::write(const u8* buf, usize, usize length)
 {
-    if (!m_reader) return length;
+    if (!m_reader)
+    {
+        Scheduler::current()->send_signal(SIGPIPE);
+        return err(EPIPE);
+    }
 
     u8* slice = TRY(m_data_buffer.slice_at_end(length));
     memcpy(slice, buf, length);

kernel/src/fs/ext2/FileSystem.cpp

@@ -63,7 +63,7 @@ namespace Ext2
 
 #ifdef EXT2_DEBUG
         kdbgln("ext2: Read inode %lu with mode %#x (%#x + %#o), size %lu", inum, inode->m_raw_inode.mode,
-               inode->m_raw_inode.mode & 0xf000, inode->mode(), inode->size());
+               inode->m_raw_inode.mode & 0xf000, inode->metadata().mode, inode->metadata().size);
 #endif
 
         m_inode_cache.try_set(inum, inode);

kernel/src/fs/ext2/Inode.cpp

@@ -91,19 +91,18 @@ namespace Ext2
         const usize inode_size = m_metadata.size;
         const usize block_size = m_fs->m_block_size;
 
-        u8* const buf = (u8*)TRY(calloc_impl(block_size, 1));
+        auto buf = TRY(Buffer::create_sized(block_size));
-        auto guard = make_scope_guard([buf] { free_impl(buf); });
 
         m_entries.clear();
 
         for (usize offset = 0; offset < inode_size; offset += block_size)
         {
-            TRY(read(buf, offset, block_size));
+            TRY(read(buf.data(), offset, block_size));
 
             usize dir_offset = 0;
             while (dir_offset < block_size)
             {
-                auto& entry = *(Ext2::RawDirectoryEntry*)&buf[dir_offset];
+                auto& entry = *(Ext2::RawDirectoryEntry*)&buf.data()[dir_offset];
 
                 if (entry.inum != 0)
                 {

kernel/src/sys/exec.cpp

@@ -182,7 +182,7 @@ Result<u64> sys_fork(Registers* regs, SyscallArgs)
     Scheduler::add_thread(thread);
 
 #ifdef FORK_DEBUG
-    kdbgln("fork: thread %lu forked into child %lu", current->id, thread->id);
+    kdbgln("fork: thread %d forked into child %d", current->id, thread->id);
 #endif
 
     return thread->id;

kernel/src/thread/Scheduler.cpp

@@ -183,7 +183,7 @@ namespace Scheduler
         CPU::disable_interrupts();
 
 #ifdef REAP_DEBUG
-        kdbgln("reap: reaping thread with id %zu", thread->id);
+        kdbgln("reap: reaping thread with id %d", thread->id);
 #endif
 
         if (thread->is_kernel)

libc/include/stdio.h

@@ -27,6 +27,7 @@ typedef struct
         int mode;        // The buffering mode.
     } _buf;
     int _flags; // The file access mode with which the file was opened.
+    pid_t _pid; // For popen(3) files, the pid of the child process.
 } FILE;
 
 #define EOF -1
@@ -52,6 +53,7 @@ extern "C"
 {
 #endif
 
+    /* Flush a stream's buffers. */
     int fflush(FILE*);
 
     /* Open a file and bind a stream to it. */
@@ -201,6 +203,9 @@ extern "C"
     /* Move a file's location across a file system. */
     int rename(const char* oldpath, const char* newpath);
 
+    /* Pipe a stream to or from a process. */
+    FILE* popen(const char* command, const char* type);
+
 #ifdef __cplusplus
 }
 #endif

libc/src/stdio.cpp

@@ -6,6 +6,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/syscall.h>
+#include <sys/wait.h>
 #include <unistd.h>
 
 FILE* stdin = nullptr;
@@ -761,4 +762,87 @@ extern "C"
         unlink(oldpath);
         return 0;
     }
+
+    FILE* popen(const char* command, const char* type)
+    {
+        int pfds[2];
+        if (pipe(pfds) < 0) return nullptr;
+
+        if (*type != 'r' && *type != 'w')
+        {
+            errno = EINVAL;
+            return nullptr;
+        }
+
+        pid_t child = fork();
+        if (child < 0)
+        {
+            close(pfds[0]);
+            close(pfds[1]);
+            return nullptr;
+        }
+        if (child == 0)
+        {
+            if (*type == 'r')
+            {
+                close(pfds[0]);
+                dup2(pfds[1], STDOUT_FILENO);
+            }
+            else
+            {
+                close(pfds[1]);
+                dup2(pfds[0], STDIN_FILENO);
+            }
+
+            execl("/bin/sh", "sh", "-c", command, nullptr);
+            _exit(127);
+        }
+
+        int fd;
+        if (*type == 'r')
+        {
+            close(pfds[1]);
+            fd = pfds[0];
+        }
+        else
+        {
+            close(pfds[0]);
+            fd = pfds[1];
+        }
+
+        int err = errno;
+        FILE* f = (FILE*)malloc(sizeof(FILE));
+        if (!f)
+        {
+            errno = err;
+            close(fd);
+            return nullptr;
+        }
+
+        f->_fd = fd;
+        f->_pid = child;
+        clearerr(f);
+
+        f->_flags = *type == 'r' ? O_RDONLY : O_WRONLY;
+        f->_buf.status = 0;
+        f->_buf.mode = _IOFBF;
+        f->_buf.size = f->_buf.index = 0;
+        f->_buf.buffer = nullptr;
+        setvbuf(f, NULL, f->_buf.mode, 0);
+
+        s_open_files[fd] = f;
+
+        return f;
+    }
+
+    int pclose(FILE* stream)
+    {
+        pid_t pid = stream->_pid;
+        fclose(stream);
+
+        int status;
+        if (waitpid(pid, &status, 0) < 0) return -1;
+
+        return status;
+    }
 }

libluna/include/luna/CRC32.h

@@ -1,7 +1,13 @@
 #pragma once
 #include <luna/Types.h>
 
-namespace CRC32
+class CRC32
 {
-    u32 checksum(const u8* data, usize size);
+  public:
-}
+    void append(const u8* data, usize size);
+
+    u32 digest();
+
+  private:
+    u32 m_checksum = 0xffffffffu;
+};

libluna/src/CRC32.cpp

@@ -33,18 +33,16 @@ static const u32 crc_table[] = {
     0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
 };
 
-namespace CRC32
+void CRC32::append(const u8* data, usize size)
 {
-    u32 checksum(const u8* data, usize size)
-    {
-        u32 crc = 0xffffffffu;
-
     for (usize i = 0; i < size; i++)
     {
-            const u32 index = (crc & 0xff) ^ data[i];
+        const u32 index = (m_checksum & 0xff) ^ data[i];
-            crc = (crc >> 8) ^ (crc_table[index]);
+        m_checksum = (m_checksum >> 8) ^ (crc_table[index]);
+    }
 }
 
-        return ~crc;
+u32 CRC32::digest()
-    }
+{
+    return ~m_checksum;
 }