Merge branch 'feature/downloader'

exercises/README.md

@@ -47,6 +47,20 @@ This is an organized list of all exercises completed so far, including a brief d
 
 ---
 
+## 📥 downloader
+
+**Description**: A multi-threaded simulated file downloader implemented in C using POSIX threads (pthreads).
+
+- 📄 [README](downloader/README.md)  
+- 📂 Directory: `downloader/`  
+- ✅ Features:
+  - Each thread simulates downloading a file by printing periodic progress updates
+  - Synchronization using `pthread` APIs
+  - Demonstrates creation, execution, and joining of threads
+  - Makefile included with standard targets
+
+---
+
 ## 🔧 Tooling & Automation
 
 **Shared tools and scripts used across projects**:
@@ -56,4 +70,4 @@ This is an organized list of all exercises completed so far, including a brief d
 - Shell script for automated tests: `run_tests.sh`
 - Valgrind memory check reports generated automatically
 
-*Last updated: 2025-07-09*
+*Last updated: 2025-07-30*

exercises/downloader/Makefile

@@ -0,0 +1,27 @@
+# Makefile for Multi-threaded File Downloader
+
+CC      := gcc
+CFLAGS  := -Wall -Wextra -pedantic -std=c11 -pthread -g
+TARGET  := downloader
+SRC     := main.c
+OBJS    := $(SRC:.c=.o)
+
+.PHONY: all clean test valgrind
+
+all: $(TARGET)
+
+$(TARGET): $(OBJS)
+	$(CC) $(CFLAGS) -o $@ $^
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+test: $(TARGET)
+	./downloader test1.txt test2.txt test3.txt
+
+valgrind: $(TARGET)
+	valgrind --leak-check=full ./downloader test1.txt test2.txt
+
+clean:
+	rm -f $(TARGET) $(OBJS)
+

exercises/downloader/README.md

@@ -0,0 +1,89 @@
+# 🧵 Multi-threaded File Downloader (Simulated)
+
+This project simulates a multi-threaded file downloader in C using POSIX threads (`pthreads`). The goal is to practice creating and managing threads, synchronizing access to shared resources, and simulating parallel file downloads.
+
+---
+
+## 📋 Description
+
+Each file provided via command-line arguments is "downloaded" by a separate thread. The download is simulated by printing log messages and sleeping for a random duration. All threads run concurrently and the main thread waits for them to complete.
+
+This project is inspired by Chapter 7 ("Threads") of *Linux System Programming* by Robert Love.
+
+---
+
+## 🚀 Usage
+
+```bash
+$ ./downloader file1.txt file2.txt file3.txt
+````
+
+Each file will be "downloaded" in parallel by a separate thread. The program prints informative messages about the start and completion of each download.
+
+---
+
+## 🛠️ Features
+
+* One thread per file
+* Simulated download using `sleep()`
+* Optional logging to file (future enhancement)
+* Thread-safe output via `pthread_mutex_t`
+* Clean thread termination via `pthread_join`
+
+---
+
+## 🧪 Example Output
+
+```
+[Thread 0x7fdc9a10]: Starting download of file1.txt
+[Thread 0x7fdc9210]: Starting download of file2.txt
+[Thread 0x7fdc9210]: Finished download of file2.txt
+[Thread 0x7fdc9a10]: Finished download of file1.txt
+All downloads complete.
+```
+
+---
+
+## 📂 Project Structure
+
+```
+multidownload/
+├── main.c         # Main program
+├── Makefile       # Build script
+└── README.md      # Project documentation
+```
+
+---
+
+## 🧵 Concepts Practiced
+
+* Thread creation with `pthread_create`
+* Thread joining with `pthread_join`
+* Synchronization with `pthread_mutex_t`
+* Struct-based thread argument passing
+* Output race condition prevention
+
+---
+
+## 🏗️ Build
+
+```bash
+$ make
+```
+
+To clean the build:
+
+```bash
+$ make clean
+```
+
+---
+
+## 📖 References
+
+* *Linux System Programming* by Robert Love — Chapter 7: Threads
+* POSIX Threads (man 7 pthread)
+
+---
+
+*Last updated: 2025-07-28*

exercises/downloader/main.c

@@ -0,0 +1,41 @@
+#define _GNU_SOURCE
+#include <pthread.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+static void *download(void *);
+
+int main(int argc, char *argv[])
+{
+	if (argc < 2) {
+		fprintf(stderr, "Usage: %s file1 file2...", argv[0]);
+		return 1;
+	}
+
+	const int nfile = argc - 1;
+	pthread_t workers[nfile];
+	for (int i = 0; i < nfile; i++) {
+		pthread_create(&workers[i], NULL, download, argv[i + 1]);
+	}
+
+	for (int i = 0; i < nfile; i++) {
+		pthread_join(workers[i], NULL);
+	}
+	printf("All downloads complete.\n");
+
+	return 0;
+}
+
+static void *download(void *arg)
+{
+	char *uri = (char *)arg;
+	int tid = syscall(SYS_gettid);
+	printf("[Thread %x] Starting download of %s\n", tid, uri);
+	sleep(rand() % 3 + 1);
+	printf("[Thread %x] Finished download of %s\n", tid, uri);
+	pthread_exit(0);
+}