btrfs_shell: Added cat command

src/tools/btrfs_shell/Jamfile

@@ -26,8 +26,11 @@ if ! $(HOST_PLATFORM_BEOS_COMPATIBLE) {
 	fsShellCommandLibs = $(HOST_NETWORK_LIBS) ;
 }
 
+UseHeaders [ FDirName $(HAIKU_TOP) headers build ] : true ;
+
 if ! $(HOST_PLATFORM_BEOS_COMPATIBLE) {
 	UseHeaders [ FDirName $(HAIKU_TOP) headers build os ] : true ;
+	UseHeaders [ FDirName $(HAIKU_TOP) headers build os support ] : true ;
 }
 
 UsePrivateHeaders shared storage fs_shell ;
@@ -50,6 +53,8 @@ BuildPlatformMergeObject <build>btrfs.o : $(btrfsSources) ;
 
 BuildPlatformMain <build>btrfs_shell
 	:
+	additional_commands.cpp
+	command_cat.cpp
 	:
 	<build>btrfs.o
 	<build>fs_shell.a $(libHaikuCompat) $(HOST_LIBSUPC++) $(HOST_LIBSTDC++)

src/tools/btrfs_shell/additional_commands.cpp

@@ -0,0 +1,19 @@
+#include "fssh.h"
+
+#include "command_cat.h"
+
+
+namespace FSShell {
+
+
+void
+register_additional_commands()
+{
+	CommandManager::Default()->AddCommands(
+		command_cat,	"cat",	"concatenate file(s) to stdout",
+		NULL
+	);
+}
+
+
+}	// namespace FSShell

src/tools/btrfs_shell/command_cat.cpp

@@ -0,0 +1,61 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "syscalls.h"
+#include "system_dependencies.h"
+
+
+namespace FSShell {
+
+
+fssh_status_t
+command_cat(int argc, const char* const* argv)
+{
+	long numBytes = 10;
+	int fileStart = 1;
+	if (argc < 2 || strcmp(argv[1], "--help") == 0) {
+		printf(
+			"Usage: %s [ -n ] [FILE]...\n"
+			"\t -n\tNumber of bytes to read\n",
+			argv[0]
+		);
+		return FSSH_B_OK;
+	}
+
+	if (argc > 3 && strcmp(argv[1], "-n") == 0) {
+		fileStart += 2;
+		numBytes = strtol(argv[2], NULL, 10);
+	}
+
+	const char* const* files = argv + fileStart;
+	for (; *files; files++) {
+		const char* file = *files;
+		int fd = _kern_open(-1, file, O_RDONLY, O_RDONLY);
+		if (fd < 0) {
+			fssh_dprintf("Error: %s\n", fssh_strerror(fd));
+			return FSSH_B_BAD_VALUE;
+		}
+
+		char buffer[numBytes + 1];
+		if (buffer == NULL) {
+			fssh_dprintf("Error: No memory\n");
+			_kern_close(fd);
+			return FSSH_B_NO_MEMORY;
+		}
+
+		if (_kern_read(fd, 0, buffer, numBytes) != numBytes) {
+			fssh_dprintf("Error: fail to read, length: %i\n", numBytes);
+			_kern_close(fd);
+			return FSSH_B_BAD_VALUE;
+		}
+
+		_kern_close(fd);
+		buffer[numBytes] = '\0';
+		printf("%s\n", buffer);
+	}
+
+	return FSSH_B_OK;
+}
+
+
+}	// namespace FSShell

src/tools/btrfs_shell/command_cat.h

@@ -0,0 +1,17 @@
+#ifndef COMMAND_CAT_H
+#define COMMAND_CAT_H
+
+
+#include "fssh_types.h"
+
+
+namespace FSShell {
+
+
+fssh_status_t command_cat(int argc, const char* const* argv);
+
+
+}	// namespace FSShell
+
+
+#endif	// COMMAND_CAT_H