1 files changed, 491 insertions, 0 deletions
diff --git a/prism/source.c b/prism/source.c
new file mode 100644
index 0000000000..f61cb19c1b
--- /dev/null
+++ b/prism/source.c
@@ -0,0 +1,491 @@
+#include "prism/internal/source.h"
+
+#include "prism/internal/allocator.h"
+#include "prism/internal/buffer.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+/* The following headers are necessary to read files using demand paging. */
+#ifdef _WIN32
+#include <windows.h>
+#elif defined(_POSIX_MAPPED_FILES)
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#elif defined(PRISM_HAS_FILESYSTEM)
+#include <fcntl.h>
+#include <sys/stat.h>
+#endif
+
+static const uint8_t empty_source[] = "";
+
+/**
+ * Allocate and initialize a pm_source_t with the given fields.
+ */
+static pm_source_t *
+pm_source_alloc(const uint8_t *source, size_t length, pm_source_type_t type) {
+    pm_source_t *result = xmalloc(sizeof(pm_source_t));
+    if (result == NULL) abort();
+
+    *result = (struct pm_source_t) {
+        .source = source,
+        .length = length,
+        .type = type
+    };
+
+    return result;
+}
+
+/**
+ * Create a new source that wraps existing constant memory.
+ */
+pm_source_t *
+pm_source_constant_new(const uint8_t *data, size_t length) {
+    return pm_source_alloc(data, length, PM_SOURCE_CONSTANT);
+}
+
+/**
+ * Create a new source that wraps existing shared memory.
+ */
+pm_source_t *
+pm_source_shared_new(const uint8_t *data, size_t length) {
+    return pm_source_alloc(data, length, PM_SOURCE_SHARED);
+}
+
+/**
+ * Create a new source that owns its memory.
+ */
+pm_source_t *
+pm_source_owned_new(uint8_t *data, size_t length) {
+    return pm_source_alloc(data, length, PM_SOURCE_OWNED);
+}
+
+#ifdef _WIN32
+/**
+ * Represents a file handle on Windows, where the path will need to be freed
+ * when the file is closed.
+ */
+typedef struct {
+    /** The path to the file, which will become allocated memory. */
+    WCHAR *path;
+
+    /** The size of the allocated path in bytes. */
+    size_t path_size;
+
+    /** The handle to the file, which will start as uninitialized memory. */
+    HANDLE file;
+} pm_source_file_handle_t;
+
+/**
+ * Open the file indicated by the filepath parameter for reading on Windows.
+ */
+static pm_source_init_result_t
+pm_source_file_handle_open(pm_source_file_handle_t *handle, const char *filepath) {
+    int length = MultiByteToWideChar(CP_UTF8, 0, filepath, -1, NULL, 0);
+    if (length == 0) return PM_SOURCE_INIT_ERROR_GENERIC;
+
+    handle->path_size = sizeof(WCHAR) * ((size_t) length);
+    handle->path = xmalloc(handle->path_size);
+    if ((handle->path == NULL) || (MultiByteToWideChar(CP_UTF8, 0, filepath, -1, handle->path, length) == 0)) {
+        xfree_sized(handle->path, handle->path_size);
+        return PM_SOURCE_INIT_ERROR_GENERIC;
+    }
+
+    handle->file = CreateFileW(handle->path, GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_READONLY, NULL);
+    if (handle->file == INVALID_HANDLE_VALUE) {
+        pm_source_init_result_t result = PM_SOURCE_INIT_ERROR_GENERIC;
+
+        if (GetLastError() == ERROR_ACCESS_DENIED) {
+            DWORD attributes = GetFileAttributesW(handle->path);
+            if ((attributes != INVALID_FILE_ATTRIBUTES) && (attributes & FILE_ATTRIBUTE_DIRECTORY)) {
+                result = PM_SOURCE_INIT_ERROR_DIRECTORY;
+            }
+        }
+
+        xfree_sized(handle->path, handle->path_size);
+        return result;
+    }
+
+    return PM_SOURCE_INIT_SUCCESS;
+}
+
+/**
+ * Close the file handle and free the path.
+ */
+static void
+pm_source_file_handle_close(pm_source_file_handle_t *handle) {
+    xfree_sized(handle->path, handle->path_size);
+    CloseHandle(handle->file);
+}
+#endif
+
+/**
+ * Create a new source by memory-mapping a file.
+ */
+pm_source_t *
+pm_source_mapped_new(const char *filepath, int open_flags, pm_source_init_result_t *result) {
+#ifdef _WIN32
+    (void) open_flags;
+
+    /* Open the file for reading. */
+    pm_source_file_handle_t handle;
+    *result = pm_source_file_handle_open(&handle, filepath);
+    if (*result != PM_SOURCE_INIT_SUCCESS) return NULL;
+
+    /* Get the file size. */
+    DWORD file_size = GetFileSize(handle.file, NULL);
+    if (file_size == INVALID_FILE_SIZE) {
+        pm_source_file_handle_close(&handle);
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    /* If the file is empty, then return a constant source. */
+    if (file_size == 0) {
+        pm_source_file_handle_close(&handle);
+        *result = PM_SOURCE_INIT_SUCCESS;
+        return pm_source_alloc(empty_source, 0, PM_SOURCE_CONSTANT);
+    }
+
+    /* Create a mapping of the file. */
+    HANDLE mapping = CreateFileMapping(handle.file, NULL, PAGE_READONLY, 0, 0, NULL);
+    if (mapping == NULL) {
+        pm_source_file_handle_close(&handle);
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    /* Map the file into memory. */
+    uint8_t *source = (uint8_t *) MapViewOfFile(mapping, FILE_MAP_READ, 0, 0, 0);
+    CloseHandle(mapping);
+    pm_source_file_handle_close(&handle);
+
+    if (source == NULL) {
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    *result = PM_SOURCE_INIT_SUCCESS;
+    return pm_source_alloc(source, (size_t) file_size, PM_SOURCE_MAPPED);
+#elif defined(_POSIX_MAPPED_FILES)
+    /* Open the file for reading. */
+    int fd = open(filepath, O_RDONLY | open_flags);
+    if (fd == -1) {
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    /* Stat the file to get the file size. */
+    struct stat sb;
+    if (fstat(fd, &sb) == -1) {
+        close(fd);
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    /* Ensure it is a file and not a directory. */
+    if (S_ISDIR(sb.st_mode)) {
+        close(fd);
+        *result = PM_SOURCE_INIT_ERROR_DIRECTORY;
+        return NULL;
+    }
+
+    /*
+     * For non-regular files (pipes, character devices), return a specific
+     * error so the caller can handle reading through their own I/O layer.
+     */
+    if (!S_ISREG(sb.st_mode)) {
+        close(fd);
+        *result = PM_SOURCE_INIT_ERROR_NON_REGULAR;
+        return NULL;
+    }
+
+    /* mmap the file descriptor to virtually get the contents. */
+    size_t size = (size_t) sb.st_size;
+
+    if (size == 0) {
+        close(fd);
+        *result = PM_SOURCE_INIT_SUCCESS;
+        return pm_source_alloc(empty_source, 0, PM_SOURCE_CONSTANT);
+    }
+
+    uint8_t *source = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
+    if (source == MAP_FAILED) {
+        close(fd);
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    close(fd);
+    *result = PM_SOURCE_INIT_SUCCESS;
+    return pm_source_alloc(source, size, PM_SOURCE_MAPPED);
+#else
+    (void) open_flags;
+    return pm_source_file_new(filepath, result);
+#endif
+}
+
+/**
+ * Create a new source by reading a file into a heap-allocated buffer.
+ */
+pm_source_t *
+pm_source_file_new(const char *filepath, pm_source_init_result_t *result) {
+#ifdef _WIN32
+    /* Open the file for reading. */
+    pm_source_file_handle_t handle;
+    *result = pm_source_file_handle_open(&handle, filepath);
+    if (*result != PM_SOURCE_INIT_SUCCESS) return NULL;
+
+    /* Get the file size. */
+    const DWORD file_size = GetFileSize(handle.file, NULL);
+    if (file_size == INVALID_FILE_SIZE) {
+        pm_source_file_handle_close(&handle);
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    /* If the file is empty, return a constant source. */
+    if (file_size == 0) {
+        pm_source_file_handle_close(&handle);
+        *result = PM_SOURCE_INIT_SUCCESS;
+        return pm_source_alloc(empty_source, 0, PM_SOURCE_CONSTANT);
+    }
+
+    /* Create a buffer to read the file into. */
+    uint8_t *source = xmalloc(file_size);
+    if (source == NULL) {
+        pm_source_file_handle_close(&handle);
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    /* Read the contents of the file. */
+    DWORD bytes_read;
+    if (!ReadFile(handle.file, source, file_size, &bytes_read, NULL)) {
+        xfree_sized(source, file_size);
+        pm_source_file_handle_close(&handle);
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    /* Check the number of bytes read. */
+    if (bytes_read != file_size) {
+        xfree_sized(source, file_size);
+        pm_source_file_handle_close(&handle);
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    pm_source_file_handle_close(&handle);
+    *result = PM_SOURCE_INIT_SUCCESS;
+    return pm_source_alloc(source, (size_t) file_size, PM_SOURCE_OWNED);
+#elif defined(PRISM_HAS_FILESYSTEM)
+    /* Open the file for reading. */
+    int fd = open(filepath, O_RDONLY);
+    if (fd == -1) {
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    /* Stat the file to get the file size. */
+    struct stat sb;
+    if (fstat(fd, &sb) == -1) {
+        close(fd);
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    /* Ensure it is a file and not a directory. */
+    if (S_ISDIR(sb.st_mode)) {
+        close(fd);
+        *result = PM_SOURCE_INIT_ERROR_DIRECTORY;
+        return NULL;
+    }
+
+    /* Check the size to see if it's empty. */
+    size_t size = (size_t) sb.st_size;
+    if (size == 0) {
+        close(fd);
+        *result = PM_SOURCE_INIT_SUCCESS;
+        return pm_source_alloc(empty_source, 0, PM_SOURCE_CONSTANT);
+    }
+
+    const size_t length = (size_t) size;
+    uint8_t *source = xmalloc(length);
+    if (source == NULL) {
+        close(fd);
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    ssize_t bytes_read = read(fd, source, length);
+    close(fd);
+
+    if (bytes_read == -1 || (size_t) bytes_read != length) {
+        xfree_sized(source, length);
+        *result = PM_SOURCE_INIT_ERROR_GENERIC;
+        return NULL;
+    }
+
+    *result = PM_SOURCE_INIT_SUCCESS;
+    return pm_source_alloc(source, length, PM_SOURCE_OWNED);
+#else
+    (void) filepath;
+    *result = PM_SOURCE_INIT_ERROR_GENERIC;
+    perror("pm_source_file_new is not implemented for this platform");
+    return NULL;
+#endif
+}
+
+/**
+ * Create a new source by reading from a stream. This allocates the source
+ * but does not read from the stream yet. Use pm_source_stream_read to read
+ * data.
+ */
+pm_source_t *
+pm_source_stream_new(void *stream, pm_source_stream_fgets_t *fgets, pm_source_stream_feof_t *feof) {
+    pm_source_t *source = pm_source_alloc(NULL, 0, PM_SOURCE_STREAM);
+    source->stream.buffer = pm_buffer_new();
+    source->stream.stream = stream;
+    source->stream.fgets = fgets;
+    source->stream.feof = feof;
+    source->stream.eof = false;
+
+    return source;
+}
+
+/**
+ * Read from the stream into the source's internal buffer until __END__ is
+ * encountered or EOF is reached. Updates the source pointer and length.
+ *
+ * Returns true if EOF was reached, false if __END__ was encountered.
+ */
+bool
+pm_source_stream_read(pm_source_t *source) {
+    pm_buffer_t *buffer = source->stream.buffer;
+
+#define LINE_SIZE 4096
+    char line[LINE_SIZE];
+
+    while (memset(line, '\n', LINE_SIZE), source->stream.fgets(line, LINE_SIZE, source->stream.stream) != NULL) {
+        size_t length = LINE_SIZE;
+        while (length > 0 && line[length - 1] == '\n') length--;
+
+        if (length == LINE_SIZE) {
+            /*
+             * If we read a line that is the maximum size and it doesn't end
+             * with a newline, then we'll just append it to the buffer and
+             * continue reading.
+             */
+            length--;
+            pm_buffer_append_string(buffer, line, length);
+            continue;
+        }
+
+        /* Append the line to the buffer. */
+        length--;
+        pm_buffer_append_string(buffer, line, length);
+
+        /*
+         * Check if the line matches the __END__ marker. If it does, then stop
+         * reading and return false. In most circumstances, this means we should
+         * stop reading from the stream so that the DATA constant can pick it
+         * up.
+         */
+        switch (length) {
+            case 7:
+                if (strncmp(line, "__END__", 7) == 0) {
+                    source->source = (const uint8_t *) pm_buffer_value(buffer);
+                    source->length = pm_buffer_length(buffer);
+                    return false;
+                }
+                break;
+            case 8:
+                if (strncmp(line, "__END__\n", 8) == 0) {
+                    source->source = (const uint8_t *) pm_buffer_value(buffer);
+                    source->length = pm_buffer_length(buffer);
+                    return false;
+                }
+                break;
+            case 9:
+                if (strncmp(line, "__END__\r\n", 9) == 0) {
+                    source->source = (const uint8_t *) pm_buffer_value(buffer);
+                    source->length = pm_buffer_length(buffer);
+                    return false;
+                }
+                break;
+        }
+
+        /*
+         * All data should be read via gets. If the string returned by gets
+         * _doesn't_ end with a newline, then we assume we hit EOF condition.
+         */
+        if (source->stream.feof(source->stream.stream)) {
+            break;
+        }
+    }
+
+#undef LINE_SIZE
+
+    source->stream.eof = true;
+    source->source = (const uint8_t *) pm_buffer_value(buffer);
+    source->length = pm_buffer_length(buffer);
+    return true;
+}
+
+/**
+ * Returns whether the stream source has reached EOF.
+ */
+bool
+pm_source_stream_eof(const pm_source_t *source) {
+    return source->stream.eof;
+}
+
+/**
+ * Free the given source and any memory it owns.
+ */
+void
+pm_source_free(pm_source_t *source) {
+    switch (source->type) {
+        case PM_SOURCE_CONSTANT:
+        case PM_SOURCE_SHARED:
+            /* No cleanup needed for the data. */
+            break;
+        case PM_SOURCE_OWNED:
+            xfree_sized((void *) source->source, source->length);
+            break;
+        case PM_SOURCE_MAPPED:
+#if defined(_WIN32)
+            if (source->length > 0) {
+                UnmapViewOfFile((void *) source->source);
+            }
+#elif defined(_POSIX_MAPPED_FILES)
+            if (source->length > 0) {
+                munmap((void *) source->source, source->length);
+            }
+#endif
+            break;
+        case PM_SOURCE_STREAM:
+            pm_buffer_free(source->stream.buffer);
+            break;
+    }
+
+    xfree_sized(source, sizeof(pm_source_t));
+}
+
+/**
+ * Returns the length of the source data in bytes.
+ */
+size_t
+pm_source_length(const pm_source_t *source) {
+    return source->length;
+}
+
+/**
+ * Returns a pointer to the source data.
+ */
+const uint8_t *
+pm_source_source(const pm_source_t *source) {
+    return source->source;
+}