Feature/pidof (#31)

* Added killall command

* Fixed feedbacks of awesomekling

* Implemented pidof program and helper to parse arguments called ArgsParser.

* Fixed feedbacks in pidof implem.

Fixes #26

5 files changed, 329 insertions, 2 deletions

diff --git a/AK/ArgsParser.cpp b/AK/ArgsParser.cpp
new file mode 100644
index 0000000000..719ca1854f
--- /dev/null
+++ b/AK/ArgsParser.cpp
@@ -0,0 +1,175 @@
+#include "ArgsParser.h"
+#include "StringBuilder.h"
+
+#include <stdio.h>
+
+namespace AK {
+
+    bool ArgsParserResult::is_present(const String& arg_name) const
+    {
+	return m_args.contains(arg_name);
+    }
+
+    String ArgsParserResult::get(const String& arg_name) const
+    {
+	return m_args.get(arg_name);
+    }
+
+    const Vector<String>& ArgsParserResult::get_single_values() const
+    {
+	return m_single_values;
+    }
+  
+    ArgsParser::Arg::Arg(const String& name, const String& description, bool required)
+	: name(name), description(description), required(required) {}
+    
+    ArgsParser::Arg::Arg(const String& name, const String& value_name, const String& description, bool required)
+	: name(name), description(description), value_name(value_name), required(required) {}
+
+    ArgsParser::ArgsParser(const String& program_name, const String& prefix)
+	: m_program_name(program_name), m_prefix(prefix) {}
+
+    ArgsParserResult ArgsParser::parse(const int argc, const char** argv) 
+    {
+	ArgsParserResult res;
+
+	// We should have at least one parameter
+	if (argc < 2)
+	    return {};
+
+	// We parse the first parameter at the index 1
+	if (parse_next_param(1, argv, argc - 1, res) != 0)
+	    return {};
+
+	if (!check_required_args(res))
+	    return {};
+
+	return res;
+    }
+
+    int ArgsParser::parse_next_param(const int index, const char** argv, const int params_left, ArgsParserResult& res) 
+    {
+	if (params_left == 0)
+	    return 0;
+
+	String param = argv[index];
+	
+	// We check if the prefix is found at the beginning of the param name
+	if (is_param_valid(param)) {
+	    auto prefix_length = m_prefix.length();
+	    String param_name = param.substring(prefix_length, param.length() - prefix_length);
+	    
+	    auto arg = m_args.find(param_name);
+	    if (arg == m_args.end()) {
+		printf("Unknown arg \"");
+		if (!param_name.is_null())
+		    printf("%s", param_name.characters());
+		printf("\"\n");
+		return -1;
+	    }
+
+	    // If this parameter must be followed by a value, we look for it
+	    if (!arg->value.value_name.is_null()) {
+		if (params_left < 1) {
+		    printf("Missing value for argument %s\n", arg->value.name.characters());
+		    return -1;
+		}
+
+		String next = String(argv[index + 1]);
+
+		if (is_param_valid(next)) {
+		    printf("Missing value for argument %s\n", arg->value.name.characters());
+		    return -1;
+		}
+
+		res.m_args.set(arg->value.name, next);
+
+		return parse_next_param(index + 2, argv, params_left - 2, res);
+	    }
+	    
+	    // Single argument, not followed by a value
+	    res.m_args.set(arg->value.name, "");
+	    
+	    return parse_next_param(index + 1, argv, params_left - 1, res);
+	}
+	
+	// Else, it's a value alone, a file name parameter for example
+	res.m_single_values.append(param);
+	
+	return parse_next_param(index + 1, argv, params_left - 1, res);
+    }
+
+    bool ArgsParser::is_param_valid(const String& param_name)
+    {
+	return param_name.substring(0, m_prefix.length()) == m_prefix;
+    }
+
+    bool ArgsParser::check_required_args(const ArgsParserResult& res)
+    {
+	for (auto& it : m_args) {
+	    if (it.value.required) {
+		if (!res.is_present(it.value.name))
+		    return false;
+	    }
+	}
+	return true;
+    }
+
+    void ArgsParser::add_arg(const String& name, const String& description, bool required)
+    {
+	m_args.set(name, Arg(name, description, required));
+    }
+
+    void ArgsParser::add_arg(const String& name, const String& value_name, const String& description, bool required)
+    {
+	m_args.set(name, Arg(name, value_name, description, required));
+    }
+
+    String ArgsParser::get_usage() const
+    {
+	StringBuilder sb;
+
+	sb.append("usage : ");
+	sb.append(m_program_name);
+	sb.append(" ");
+
+	for (auto& it : m_args) {
+	    if (it.value.required)
+		sb.append("<");
+	    else
+		sb.append("[");
+	    sb.append(m_prefix);
+	    sb.append(it.value.name);
+	    if (!it.value.value_name.is_null()) {
+		sb.append(" ");
+		sb.append(it.value.value_name);
+	    }
+	    if (it.value.required)
+		sb.append("> ");
+	    else
+		sb.append("] ");
+	}
+
+	sb.append("\n");
+
+	for (auto& it : m_args) {
+	    sb.append("    ");
+	    sb.append(m_prefix);
+	    sb.append(it.value.name);
+	    if (!it.value.value_name.is_null()) {
+		sb.append(" ");
+		sb.append(it.value.value_name);
+	    }
+	    sb.append(" : ");
+	    sb.append(it.value.description);
+	    sb.append("\n");
+	}
+
+	return sb.to_string();
+    }
+
+    void ArgsParser::print_usage() const
+    {
+	printf("%s\n", get_usage().characters());
+    }
+}
diff --git a/AK/ArgsParser.h b/AK/ArgsParser.h
new file mode 100644
index 0000000000..94ae55e7f9
--- /dev/null
+++ b/AK/ArgsParser.h
@@ -0,0 +1,61 @@
+#pragma once
+
+#include "AKString.h"
+#include "HashMap.h"
+#include "Vector.h"
+
+/*
+  The class ArgsParser provides a way to parse arguments by using a given list that describes the possible
+  types of arguments (name, description, required or not, must be followed by a value...).
+  Call the add_arg() functions to describe your arguments.
+
+  The class ArgsParserResult is used to manipulate the arguments (checking if an arg has been provided,
+  retrieve its value...). In case of error (missing required argument) an empty structure is returned as result.
+*/
+
+namespace AK {
+    class ArgsParserResult {
+    public:
+	bool is_present(const String& arg_name) const;
+	String get(const String& arg_name) const;
+	const Vector<String>& get_single_values() const;
+
+    private:
+	HashMap<String, String> m_args;
+	Vector<String> m_single_values;
+
+	friend class ArgsParser;
+    };
+
+    class ArgsParser {
+    public:
+	ArgsParser(const String& program_name, const String& prefix);
+
+	ArgsParserResult parse(const int argc, const char** argv);
+
+	void add_arg(const String& name, const String& description, bool required);
+	void add_arg(const String& name, const String& value_name, const String& description, bool required);
+	String get_usage() const;
+	void print_usage() const;
+
+    private:
+	struct Arg {
+	    inline Arg() {}
+	    Arg(const String& name, const String& description, bool required);
+	    Arg(const String& name, const String& value_name, const String& description, bool required);
+
+	    String name;
+	    String description;
+	    String value_name;
+	    bool required;
+	};
+
+	int parse_next_param(const int index, const char** argv, const int params_left, ArgsParserResult& res);
+	bool is_param_valid(const String& param_name);
+	bool check_required_args(const ArgsParserResult& res);
+
+	String m_program_name;
+	String m_prefix;
+	HashMap<String, Arg> m_args;
+    };
+}
diff --git a/Kernel/Makefile b/Kernel/Makefile
index 265b143cb0..af0321c651 100644
--- a/Kernel/Makefile
+++ b/Kernel/Makefile
@@ -75,7 +75,8 @@ AK_OBJS = \
     ../AK/StringBuilder.o \
     ../AK/StringView.o \
     ../AK/FileSystemPath.o \
-    ../AK/StdLibExtras.o
+    ../AK/StdLibExtras.o \
+    ../AK/ArgsParser.o
 
 CXX_OBJS = $(KERNEL_OBJS) $(VFS_OBJS) $(AK_OBJS)
 OBJS = $(CXX_OBJS) Boot/boot.ao
diff --git a/LibC/Makefile b/LibC/Makefile
index ab307c5cbd..acdc8c0d15 100644
--- a/LibC/Makefile
+++ b/LibC/Makefile
@@ -7,7 +7,8 @@ AK_OBJS = \
     ../AK/StringBuilder.o \
     ../AK/FileSystemPath.o \
     ../AK/StdLibExtras.o \
-    ../AK/MappedFile.o
+    ../AK/MappedFile.o \
+    ../AK/ArgsParser.o
 
 LIBC_OBJS = \
        SharedBuffer.o \
diff --git a/Userland/pidof.cpp b/Userland/pidof.cpp
new file mode 100644
index 0000000000..ab15a05417
--- /dev/null
+++ b/Userland/pidof.cpp
@@ -0,0 +1,89 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <LibCore/CFile.h>
+#include <AK/AKString.h>
+#include <AK/Vector.h>
+#include <AK/ArgsParser.h>
+
+static int pid_of(const String& process_name, bool single_shot, bool omit_pid, pid_t pid)
+{
+    bool displayed_at_least_one = false;
+
+    CFile file("/proc/all");
+    if (!file.open(CIODevice::ReadOnly)) {
+	fprintf(stderr, "pidof failed to open /proc/all\n");
+	return 2;
+    }
+
+    for (;;) {
+	auto line = file.read_line(1024);
+		
+	if (line.is_empty())
+	    break;
+
+	auto chomped = String((const char*)line.pointer(), line.size() - 1, Chomp);
+	auto parts = chomped.split_view(',');
+
+	if (parts.size() < 18)
+	    break;
+
+	bool ok = false;
+	pid_t current_pid = parts[0].to_uint(ok);
+	String name = parts[11];
+
+	if (!ok) {
+	    fprintf(stderr, "pidof failed : couldn't convert %s to a valid pid\n", parts[0].characters());
+	    return 3;
+	}
+		
+	if (name == process_name) {	
+	    if (!omit_pid || (omit_pid && current_pid != pid)) {
+		printf("%d ", current_pid);
+		displayed_at_least_one = true;
+
+		if (single_shot)
+		    break;
+	    }
+	}
+    }
+
+    if (displayed_at_least_one)
+	printf("\n");
+
+    return 0;
+}
+
+int main(int argc, char** argv)
+{
+    AK::ArgsParser args_parser("pidof", "-");
+    
+    args_parser.add_arg("s", "Single shot - this instructs the program to only return one pid", false);
+    args_parser.add_arg("o", "pid", "Tells pidof to omit processes with that pid. The special pid %PPID can be used to name the parent process of the pidof program.", false);
+    
+    AK::ArgsParserResult args = args_parser.parse(argc, (const char**)argv);
+    
+    bool s_arg = args.is_present("s");
+    bool o_arg = args.is_present("o");
+    pid_t pid = 0;
+    
+    if (o_arg) {
+        bool ok = false;
+        String pid_str = args.get("o");
+
+	if (pid_str == "%PPID")
+	    pid = getppid();
+	else
+	    pid = pid_str.to_uint(ok);
+    }
+    
+    // We should have one single value : the process name
+    Vector<String> values = args.get_single_values();
+    if (values.size() == 0) {
+	args_parser.print_usage();
+        return 0;
+    }
+    
+    return pid_of(values[0], s_arg, o_arg, pid);
+}