seems like working lab2

lab_2/Makefile

@@ -0,0 +1,27 @@
+# Makefile
+CC = gcc
+CFLAGS = -Wall -Wextra -std=c99
+LDFLAGS = -ldl
+
+# Цель по умолчанию
+all: task12 libtextlib.so
+
+# Основная программа
+task12: task12.c
+	$(CC) $(CFLAGS) -o $@ $< $(LDFLAGS)
+
+# Динамическая библиотека
+libtextlib.so: textlib.c
+	$(CC) $(CFLAGS) -fPIC -shared -o $@ $<
+
+# Очистка
+clean:
+	rm -f task12 libtextlib.so input.txt output.txt
+
+# Тест
+test: all
+	echo -e "Hello world\ntest line\nanother" > input.txt
+	./task12 input.txt output.txt 5 ./libtextlib.so
+	cat output.txt
+
+.PHONY: all clean test

lab_2/task12.c

@@ -0,0 +1,96 @@
+#include <unistd.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <dlfcn.h>
+
+#define RBUFSZ 4096
+#define WBUFSZ 4096
+
+static void die_perror(const char *what, const char *path, int exit_code) {
+    int saved = errno;
+    char msg[512];
+    if (path) {
+        snprintf(msg, sizeof(msg), "%s: %s: %s\n", what, path, strerror(saved));
+    } else {
+        snprintf(msg, sizeof(msg), "%s: %s\n", what, strerror(saved));
+    }
+    (void) write(STDERR_FILENO, msg, strlen(msg));
+    _exit(exit_code);
+}
+
+static long long parse_ll(const char *s) {
+    char *end = NULL;
+    errno = 0;
+    long long v = strtoll(s, &end, 10);
+    if (errno != 0 || end == s || *end != '\0' || v < 0) {
+        errno = EINVAL;
+        return -1;
+    }
+    return v;
+}
+
+int main(int argc, char *argv[]) {
+    if (argc != 5) {
+        const char *usage =
+                "Usage: lab2_var12 <input.txt> <output.txt> <max_replacements> <library.so>\n"
+                "Variant 12: Load text processing library dynamically and process file.\n"
+                "Library should provide 'process_text' function.\n";
+        (void) write(STDERR_FILENO, usage, strlen(usage));
+        return -1;
+    }
+
+    const char *in_path = argv[1];
+    const char *out_path = argv[2];
+    long long cap = parse_ll(argv[3]);
+    const char *lib_path = argv[4];
+
+    if (cap < 0) {
+        die_perror("invalid max_replacements", argv[3], -1);
+    }
+
+    // Динамически загружаем библиотеку
+    void *lib_handle = dlopen(lib_path, RTLD_LAZY);
+    if (!lib_handle) {
+        const char *error_msg = dlerror();
+        char msg[512];
+        snprintf(msg, sizeof(msg), "dlopen failed: %s\n", error_msg ? error_msg : "unknown error");
+        (void) write(STDERR_FILENO, msg, strlen(msg));
+        return -1;
+    }
+
+    // Получаем указатель на функцию обработки текста
+    long long (*process_text)(const char*, const char*, long long) =
+        (long long (*)(const char*, const char*, long long)) dlsym(lib_handle, "process_text");
+
+    if (!process_text) {
+        const char *error_msg = dlerror();
+        char msg[512];
+        snprintf(msg, sizeof(msg), "dlsym failed: %s\n", error_msg ? error_msg : "unknown error");
+        (void) write(STDERR_FILENO, msg, strlen(msg));
+        dlclose(lib_handle);
+        return -1;
+    }
+
+    // Вызываем функцию из библиотеки
+    long long result = process_text(in_path, out_path, cap);
+
+    if (result < 0) {
+        die_perror("process_text failed", NULL, -1);
+    }
+
+    // Закрываем библиотеку
+    dlclose(lib_handle);
+
+    // Выводим результат
+    char res[64];
+    int m = snprintf(res, sizeof(res), "%lld\n", result);
+    if (m > 0) {
+        (void) write(STDOUT_FILENO, res, (size_t) m);
+    }
+
+    return 0;
+}

lab_2/textlib.c

@@ -0,0 +1,93 @@
+#include <unistd.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+
+#define RBUFSZ 4096
+#define WBUFSZ 4096
+
+// Функция обработки текста
+long long process_text(const char *in_path, const char *out_path, long long cap) {
+    int in_fd = open(in_path, O_RDONLY);
+    if (in_fd < 0) {
+        return -1;
+    }
+
+    mode_t filePerms = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
+    int out_fd = open(out_path, O_CREAT | O_WRONLY | O_TRUNC, filePerms);
+    if (out_fd < 0) {
+        close(in_fd);
+        return -1;
+    }
+
+    char rbuf[RBUFSZ];
+    char wbuf[WBUFSZ];
+    size_t wlen = 0;
+
+    long long total_replacements = 0;
+    int at_line_start = 1;
+    unsigned char line_key = 0;
+    int replacing_enabled = 1;
+
+    for (;;) {
+        ssize_t n = read(in_fd, rbuf, sizeof(rbuf));
+        if (n > 0) {
+            for (ssize_t i = 0; i < n; i++) {
+                unsigned char c = (unsigned char) rbuf[i];
+
+                if (at_line_start) {
+                    line_key = c;
+                    at_line_start = 0;
+                }
+
+                unsigned char outc = c;
+                if (c == '\n') {
+                    at_line_start = 1;
+                } else if (replacing_enabled && c == line_key) {
+                    if (total_replacements < cap) {
+                        outc = ' ';
+                        total_replacements++;
+                        if (total_replacements == cap) {
+                            replacing_enabled = 0;
+                        }
+                    } else {
+                        replacing_enabled = 0;
+                    }
+                }
+
+                if (wlen == sizeof(wbuf)) {
+                    ssize_t wrote = write(out_fd, wbuf, wlen);
+                    if (wrote < 0 || (size_t) wrote != wlen) {
+                        close(in_fd);
+                        close(out_fd);
+                        return -1;
+                    }
+                    wlen = 0;
+                }
+                wbuf[wlen++] = (char) outc;
+            }
+        } else if (n == 0) {
+            if (wlen > 0) {
+                ssize_t wrote = write(out_fd, wbuf, wlen);
+                if (wrote < 0 || (size_t) wrote != wlen) {
+                    close(in_fd);
+                    close(out_fd);
+                    return -1;
+                }
+                wlen = 0;
+            }
+            break;
+        } else {
+            close(in_fd);
+            close(out_fd);
+            return -1;
+        }
+    }
+
+    close(in_fd);
+    close(out_fd);
+
+    return total_replacements;
+}