ringbuffer, guid, iovec stuff, and mmio

core/lib/guid.c

@@ -0,0 +1,31 @@
+#include <zinnia/guid.h>
+#include <zinnia/print.h>
+#include <string.h>
+
+bool guid_is_zero(const struct guid* guid) {
+    static const struct guid zero = {};
+    return guid_equal(guid, &zero);
+}
+
+bool guid_equal(const struct guid* a, const struct guid* b) {
+    return memcmp(a, b, sizeof(struct guid)) == 0;
+}
+
+void guid_format(const struct guid* guid, char out[static GUID_STR_LEN]) {
+    ksnprintf(
+        out,
+        GUID_STR_LEN,
+        "%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+        guid->time_low,
+        guid->time_mid,
+        guid->time_hi_version,
+        guid->clock_seq[0],
+        guid->clock_seq[1],
+        guid->node[0],
+        guid->node[1],
+        guid->node[2],
+        guid->node[3],
+        guid->node[4],
+        guid->node[5]
+    );
+}

core/lib/iovec.c

@@ -0,0 +1,53 @@
+#include <zinnia/iovec.h>
+#include <zinnia/usercopy.h>
+#include <zinnia/utils.h>
+#include <string.h>
+
+// Copies between `buf` and the iterator. If `to_iter` is set, data flows from `buf` into the iovecs.
+static errno_t iovec_iter_copy(iovec_iter_t* iter, void* buf, size_t len, bool to_iter, size_t* out_copied) {
+    size_t progress = 0;
+    errno_t status = 0;
+
+    while (progress < len && iter->current_idx < iter->iovecs_len) {
+        iovec_t* vec = &iter->iovecs[iter->current_idx];
+        size_t remaining = vec->len - iter->current_offset;
+        if (remaining == 0) {
+            iter->current_idx++;
+            iter->current_offset = 0;
+            continue;
+        }
+
+        size_t chunk = MIN(remaining, len - progress);
+        void* ptr = (void*)(vec->base + iter->current_offset);
+        uint8_t* kbuf = (uint8_t*)buf + progress;
+
+        if (iter->user) {
+            bool ok = to_iter ? usercopy_write((__user void*)ptr, kbuf, chunk)
+                              : usercopy_read(kbuf, (const __user void*)ptr, chunk);
+            if (!ok) {
+                status = EFAULT;
+                break;
+            }
+        } else if (to_iter) {
+            memcpy(ptr, kbuf, chunk);
+        } else {
+            memcpy(kbuf, ptr, chunk);
+        }
+
+        progress += chunk;
+        iter->current_offset += chunk;
+        iter->total_offset += chunk;
+    }
+
+    if (out_copied)
+        *out_copied = progress;
+    return status;
+}
+
+errno_t iovec_iter_copy_to(iovec_iter_t* iter, const void* src, size_t len, size_t* out_copied) {
+    return iovec_iter_copy(iter, (void*)src, len, true, out_copied);
+}
+
+errno_t iovec_iter_copy_from(iovec_iter_t* iter, void* dst, size_t len, size_t* out_copied) {
+    return iovec_iter_copy(iter, dst, len, false, out_copied);
+}

core/lib/meson.build

@@ -1,6 +1,10 @@
 # Freestanding libc functions that are needed in the kernel
 
 kernel_sources += files(
+    'guid.c',
+    'iovec.c',
+    'radix.c',
+    'ringbuf.c',
     'runtime.c',
     'stdlib.c',
     'string.c',

core/lib/radix.c

@@ -0,0 +1,255 @@
+#include <zinnia/alloc.h>
+#include <zinnia/radix.h>
+
+static bool covers(const struct radix_node* node, uint64_t index) {
+    return node->shift + RADIX_BITS >= 64 || (index >> (node->shift + RADIX_BITS)) == 0;
+}
+
+static size_t slot_of(const struct radix_node* node, uint64_t index) {
+    return (index >> node->shift) & (RADIX_SLOTS - 1);
+}
+
+static struct radix_node* node_alloc(uint8_t shift, struct radix_node* parent, uint8_t offset) {
+    struct radix_node* node = mem_alloc(sizeof(struct radix_node), 0);
+    if (!node)
+        return nullptr;
+    node->shift = shift;
+    node->parent = parent;
+    node->offset = offset;
+    return node;
+}
+
+static void free_subtree(struct radix_node* node) {
+    if (node->shift > 0) {
+        for (size_t i = 0; i < RADIX_SLOTS; i++) {
+            if (node->slots[i])
+                free_subtree(node->slots[i]);
+        }
+    }
+    mem_free(node);
+}
+
+void radix_init(struct radix_tree* tree) {
+    tree->root = nullptr;
+}
+
+void radix_destroy(struct radix_tree* tree) {
+    if (tree->root)
+        free_subtree(tree->root);
+    tree->root = nullptr;
+}
+
+bool radix_empty(struct radix_tree* tree) {
+    return tree->root == nullptr;
+}
+
+static struct radix_node* leaf_of(struct radix_tree* tree, uint64_t index) {
+    struct radix_node* node = tree->root;
+    if (!node || !covers(node, index))
+        return nullptr;
+    while (node->shift > 0) {
+        node = node->slots[slot_of(node, index)];
+        if (!node)
+            return nullptr;
+    }
+    return node;
+}
+
+void* radix_lookup(struct radix_tree* tree, uint64_t index) {
+    struct radix_node* leaf = leaf_of(tree, index);
+    return leaf ? leaf->slots[slot_of(leaf, index)] : nullptr;
+}
+
+void** radix_slot(struct radix_tree* tree, uint64_t index) {
+    struct radix_node* leaf = leaf_of(tree, index);
+    return leaf ? &leaf->slots[slot_of(leaf, index)] : nullptr;
+}
+
+static errno_t grow(struct radix_tree* tree, uint64_t index) {
+    if (!tree->root) {
+        uint8_t shift = 0;
+        while (shift + RADIX_BITS < 64 && (index >> (shift + RADIX_BITS)) != 0)
+            shift += RADIX_BITS;
+        tree->root = node_alloc(shift, nullptr, 0);
+        return tree->root ? 0 : ENOMEM;
+    }
+
+    while (!covers(tree->root, index)) {
+        struct radix_node* old = tree->root;
+        struct radix_node* top = node_alloc(old->shift + RADIX_BITS, nullptr, 0);
+        if (!top)
+            return ENOMEM;
+        top->slots[0] = old;
+        top->count = 1;
+        for (size_t t = 0; t < RADIX_NUM_TAGS; t++) {
+            if (old->tags[t])
+                top->tags[t] = 1;
+        }
+        old->parent = top;
+        old->offset = 0;
+        tree->root = top;
+    }
+    return 0;
+}
+
+errno_t radix_insert(struct radix_tree* tree, uint64_t index, void* value) {
+    errno_t status = grow(tree, index);
+    if (status)
+        return status;
+
+    struct radix_node* node = tree->root;
+    while (node->shift > 0) {
+        const size_t slot = slot_of(node, index);
+        struct radix_node* child = node->slots[slot];
+        if (!child) {
+            child = node_alloc(node->shift - RADIX_BITS, node, slot);
+            if (!child)
+                return ENOMEM;
+            node->slots[slot] = child;
+            node->count++;
+        }
+        node = child;
+    }
+
+    const size_t slot = slot_of(node, index);
+    if (node->slots[slot])
+        return EEXIST;
+    node->slots[slot] = value;
+    node->count++;
+    return 0;
+}
+
+static void clear_tag_upwards(struct radix_node* node, size_t slot, enum radix_tag tag) {
+    while (node) {
+        node->tags[tag] &= ~((uint64_t)1 << slot);
+        if (node->tags[tag])
+            return;
+        slot = node->offset;
+        node = node->parent;
+    }
+}
+
+void* radix_remove(struct radix_tree* tree, uint64_t index) {
+    struct radix_node* node = leaf_of(tree, index);
+    if (!node)
+        return nullptr;
+
+    size_t slot = slot_of(node, index);
+    void* value = node->slots[slot];
+    if (!value)
+        return nullptr;
+
+    for (size_t t = 0; t < RADIX_NUM_TAGS; t++) {
+        if (node->tags[t] & ((uint64_t)1 << slot))
+            clear_tag_upwards(node, slot, t);
+    }
+
+    node->slots[slot] = nullptr;
+    node->count--;
+    while (node->count == 0) {
+        struct radix_node* parent = node->parent;
+        if (!parent) {
+            tree->root = nullptr;
+            mem_free(node);
+            break;
+        }
+        slot = node->offset;
+        parent->slots[slot] = nullptr;
+        parent->count--;
+        mem_free(node);
+        node = parent;
+    }
+    return value;
+}
+
+void radix_tag_set(struct radix_tree* tree, uint64_t index, enum radix_tag tag) {
+    struct radix_node* node = leaf_of(tree, index);
+    if (!node || !node->slots[slot_of(node, index)])
+        return;
+    size_t slot = slot_of(node, index);
+    while (node) {
+        const uint64_t bit = (uint64_t)1 << slot;
+        if (node->tags[tag] & bit)
+            return;
+        node->tags[tag] |= bit;
+        slot = node->offset;
+        node = node->parent;
+    }
+}
+
+void radix_tag_clear(struct radix_tree* tree, uint64_t index, enum radix_tag tag) {
+    struct radix_node* node = leaf_of(tree, index);
+    if (!node)
+        return;
+    const size_t slot = slot_of(node, index);
+    if (node->tags[tag] & ((uint64_t)1 << slot))
+        clear_tag_upwards(node, slot, tag);
+}
+
+bool radix_tag_get(struct radix_tree* tree, uint64_t index, enum radix_tag tag) {
+    struct radix_node* node = leaf_of(tree, index);
+    return node && (node->tags[tag] & ((uint64_t)1 << slot_of(node, index)));
+}
+
+bool radix_tagged(struct radix_tree* tree, enum radix_tag tag) {
+    return tree->root && tree->root->tags[tag];
+}
+
+struct gang {
+    size_t max;
+    size_t found;
+    void** out;
+    uint64_t* out_index;
+    int tag;
+};
+
+static void gang_walk(struct radix_node* node, uint64_t base, uint64_t first, struct gang* g) {
+    size_t start = 0;
+    if (first > base) {
+        const uint64_t delta = (first - base) >> node->shift;
+        if (delta >= RADIX_SLOTS)
+            return;
+        start = delta;
+    }
+
+    for (size_t i = start; i < RADIX_SLOTS && g->found < g->max; i++) {
+        if (!node->slots[i])
+            continue;
+        if (g->tag >= 0 && !(node->tags[g->tag] & ((uint64_t)1 << i)))
+            continue;
+        const uint64_t index = base + ((uint64_t)i << node->shift);
+        if (node->shift == 0) {
+            if (g->out)
+                g->out[g->found] = node->slots[i];
+            if (g->out_index)
+                g->out_index[g->found] = index;
+            g->found++;
+        } else {
+            gang_walk(node->slots[i], index, first > index ? first : index, g);
+        }
+    }
+}
+
+static size_t gang_lookup(struct radix_tree* tree, uint64_t first, int tag, size_t max, void** out, uint64_t* idx) {
+    struct radix_node* root = tree->root;
+    if (!root || max == 0 || !covers(root, first))
+        return 0;
+    struct gang g = {.max = max, .out = out, .out_index = idx, .tag = tag};
+    gang_walk(root, 0, first, &g);
+    return g.found;
+}
+
+size_t radix_gang_lookup(struct radix_tree* tree, uint64_t first, size_t max, void** out, uint64_t* out_index) {
+    return gang_lookup(tree, first, -1, max, out, out_index);
+}
+
+size_t radix_gang_lookup_tag(
+    struct radix_tree* tree,
+    uint64_t first,
+    enum radix_tag tag,
+    size_t max,
+    void** out,
+    uint64_t* out_index
+) {
+    return gang_lookup(tree, first, tag, max, out, out_index);
+}

core/lib/ringbuf.c

@@ -0,0 +1,94 @@
+#include <zinnia/alloc.h>
+#include <zinnia/ringbuf.h>
+#include <zinnia/utils.h>
+#include <string.h>
+
+errno_t ringbuf_init(struct ringbuf* rb, size_t capacity) {
+    rb->data = mem_alloc(capacity, ALLOC_NOZERO);
+    if (!rb->data)
+        return ENOMEM;
+    rb->capacity = capacity;
+    rb->head = 0;
+    rb->len = 0;
+    return 0;
+}
+
+void ringbuf_fini(struct ringbuf* rb) {
+    mem_free(rb->data);
+    rb->data = nullptr;
+    rb->capacity = 0;
+    rb->len = 0;
+}
+
+static size_t tail(const struct ringbuf* rb) {
+    return (rb->head + rb->len) % rb->capacity;
+}
+
+static size_t write_chunk(const struct ringbuf* rb, size_t len) {
+    return MIN(len, MIN(ringbuf_space(rb), rb->capacity - tail(rb)));
+}
+
+static size_t read_chunk(const struct ringbuf* rb, size_t len) {
+    return MIN(len, MIN(rb->len, rb->capacity - rb->head));
+}
+
+static void advance_read(struct ringbuf* rb, size_t len) {
+    rb->head = (rb->head + len) % rb->capacity;
+    rb->len -= len;
+    if (rb->len == 0)
+        rb->head = 0;
+}
+
+size_t ringbuf_write(struct ringbuf* rb, const void* src, size_t len) {
+    size_t done = 0;
+    size_t chunk;
+    while ((chunk = write_chunk(rb, len - done))) {
+        memcpy(rb->data + tail(rb), (const uint8_t*)src + done, chunk);
+        rb->len += chunk;
+        done += chunk;
+    }
+    return done;
+}
+
+size_t ringbuf_read(struct ringbuf* rb, void* dst, size_t len) {
+    size_t done = 0;
+    size_t chunk;
+    while ((chunk = read_chunk(rb, len - done))) {
+        memcpy((uint8_t*)dst + done, rb->data + rb->head, chunk);
+        advance_read(rb, chunk);
+        done += chunk;
+    }
+    return done;
+}
+
+errno_t ringbuf_write_iter(struct ringbuf* rb, iovec_iter_t* iter, size_t len, size_t* out_written) {
+    size_t done = 0;
+    errno_t status = 0;
+    size_t chunk;
+    while (!status && (chunk = write_chunk(rb, len - done))) {
+        size_t copied;
+        status = iovec_iter_copy_from(iter, rb->data + tail(rb), chunk, &copied);
+        rb->len += copied;
+        done += copied;
+        if (copied < chunk)
+            break;
+    }
+    *out_written = done;
+    return done ? 0 : status;
+}
+
+errno_t ringbuf_read_iter(struct ringbuf* rb, iovec_iter_t* iter, size_t len, size_t* out_read) {
+    size_t done = 0;
+    errno_t status = 0;
+    size_t chunk;
+    while (!status && (chunk = read_chunk(rb, len - done))) {
+        size_t copied;
+        status = iovec_iter_copy_to(iter, rb->data + rb->head, chunk, &copied);
+        advance_read(rb, copied);
+        done += copied;
+        if (copied < chunk)
+            break;
+    }
+    *out_read = done;
+    return done ? 0 : status;
+}

include/zinnia/endian.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <stdint.h> // IWYU pragma: keep
+
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define cpu_to_le16(x) ((uint16_t)(x))
+#define cpu_to_le32(x) ((uint32_t)(x))
+#define cpu_to_le64(x) ((uint64_t)(x))
+#define cpu_to_be16(x) __builtin_bswap16(x)
+#define cpu_to_be32(x) __builtin_bswap32(x)
+#define cpu_to_be64(x) __builtin_bswap64(x)
+#else
+#define cpu_to_le16(x) __builtin_bswap16(x)
+#define cpu_to_le32(x) __builtin_bswap32(x)
+#define cpu_to_le64(x) __builtin_bswap64(x)
+#define cpu_to_be16(x) ((uint16_t)(x))
+#define cpu_to_be32(x) ((uint32_t)(x))
+#define cpu_to_be64(x) ((uint64_t)(x))
+#endif
+
+#define le16_to_cpu(x) cpu_to_le16(x)
+#define le32_to_cpu(x) cpu_to_le32(x)
+#define le64_to_cpu(x) cpu_to_le64(x)
+#define be16_to_cpu(x) cpu_to_be16(x)
+#define be32_to_cpu(x) cpu_to_be32(x)
+#define be64_to_cpu(x) cpu_to_be64(x)

include/zinnia/guid.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+struct [[gnu::packed]] guid {
+    uint32_t time_low;
+    uint16_t time_mid;
+    uint16_t time_hi_version;
+    uint8_t clock_seq[2];
+    uint8_t node[6];
+};
+static_assert(sizeof(struct guid) == 16);
+
+constexpr size_t GUID_STR_LEN = 37;
+
+bool guid_is_zero(const struct guid* guid);
+bool guid_equal(const struct guid* a, const struct guid* b);
+void guid_format(const struct guid* guid, char out[static GUID_STR_LEN]);

include/zinnia/iovec.h

@@ -8,31 +8,42 @@
 
 typedef struct __iovec iovec_t;
 
-struct iovec_iter {
+typedef struct {
     iovec_t* iovecs;
     size_t iovecs_len;
     size_t total_len;
     size_t total_offset;
     size_t current_idx;
     size_t current_offset;
-};
+    // Whether the iovecs point to user memory.
+    bool user;
+} iovec_iter_t;
 
-static inline size_t iovec_iter_len(struct iovec_iter* iter) {
+static inline size_t iovec_iter_len(iovec_iter_t* iter) {
     return iter->total_len - iter->total_offset;
 }
 
 // Creates an iovec iterator over kernel memory.
-static inline struct iovec_iter iovec_iter_kernel(iovec_t* iovecs, size_t count) {
+static inline iovec_iter_t iovec_iter_kernel(iovec_t* iovecs, size_t count) {
     size_t total = 0;
     for (size_t i = 0; i < count; i++)
         total += iovecs[i].len;
 
-    return (struct iovec_iter){
+    return (iovec_iter_t){
         .iovecs = iovecs,
         .iovecs_len = count,
         .total_len = total,
         .total_offset = 0,
         .current_idx = 0,
         .current_offset = 0,
+        .user = false,
     };
 }
+
+// Copies up to `len` bytes from `src` into the iterator and advances it.
+// Returns the amount of bytes actually copied in `out_copied`.
+errno_t iovec_iter_copy_to(iovec_iter_t* iter, const void* src, size_t len, size_t* out_copied);
+
+// Copies up to `len` bytes out of the iterator into `dst` and advances it.
+// Returns the amount of bytes actually copied in `out_copied`.
+errno_t iovec_iter_copy_from(iovec_iter_t* iter, void* dst, size_t len, size_t* out_copied);

include/zinnia/mmio.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <stddef.h>
 #include <stdint.h>
 
 static inline uint8_t mmio_read8(void* ptr) {
@@ -33,3 +34,105 @@ static inline void mmio_write32(void* ptr, uint32_t value) {
 static inline void mmio_write64(void* ptr, uint64_t value) {
     *((volatile uint64_t*)ptr) = value;
 }
+
+enum mmio_endian : uint8_t {
+    MMIO_NATIVE = 0,
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+    MMIO_LE = 0,
+    MMIO_BE = 1,
+#else
+    MMIO_BE = 0,
+    MMIO_LE = 1,
+#endif
+};
+
+typedef struct {
+    size_t offset;
+    enum mmio_endian endian;
+} mmio_reg8;
+
+typedef struct {
+    size_t offset;
+    enum mmio_endian endian;
+} mmio_reg16;
+
+typedef struct {
+    size_t offset;
+    enum mmio_endian endian;
+} mmio_reg32;
+
+typedef struct {
+    size_t offset;
+    enum mmio_endian endian;
+} mmio_reg64;
+
+typedef struct {
+    mmio_reg8 reg;
+    uint8_t shift;
+    uint8_t width;
+} mmio_field8;
+
+typedef struct {
+    mmio_reg16 reg;
+    uint8_t shift;
+    uint8_t width;
+} mmio_field16;
+
+typedef struct {
+    mmio_reg32 reg;
+    uint8_t shift;
+    uint8_t width;
+} mmio_field32;
+
+typedef struct {
+    mmio_reg64 reg;
+    uint8_t shift;
+    uint8_t width;
+} mmio_field64;
+
+#define MMIO_REG_ZERO(reg) \
+    _Generic((reg), mmio_reg8: (uint8_t)0, mmio_reg16: (uint16_t)0, mmio_reg32: (uint32_t)0, mmio_reg64: (uint64_t)0)
+
+#define MMIO_REG_TYPE(reg)     typeof(MMIO_REG_ZERO(reg))
+#define MMIO_FIELD_TYPE(field) MMIO_REG_TYPE((field).reg)
+
+#define mmio_bswap(value) \
+    _Generic( \
+        (value), \
+        uint8_t: (value), \
+        uint16_t: __builtin_bswap16(value), \
+        uint32_t: __builtin_bswap32(value), \
+        uint64_t: __builtin_bswap64(value) \
+    )
+
+#define mmio_width_mask(width) ((width) >= 64 ? UINT64_MAX : ((uint64_t)1 << (width)) - 1)
+
+// Reads an MMIO register.
+#define mmio_reg_read(base, reg) \
+    ({ \
+        auto __mmio_rr = (reg); \
+        typedef MMIO_REG_TYPE(__mmio_rr) __mmio_rt; \
+        __mmio_rt __mmio_rv = *(volatile __mmio_rt*)((uint8_t*)(base) + __mmio_rr.offset); \
+        (__mmio_rt)(__mmio_rr.endian ? mmio_bswap(__mmio_rv) : __mmio_rv); \
+    })
+
+// Writes a value to an MMIO register.
+#define mmio_reg_write(base, reg, value) \
+    ({ \
+        auto __mmio_rw = (reg); \
+        static_assert( \
+            sizeof(value) <= sizeof(MMIO_REG_TYPE(reg)), \
+            "High bits of the value might get truncated. Explicitly cast if this is intended." \
+        ); \
+        typedef MMIO_REG_TYPE(__mmio_rw) __mmio_wt; \
+        __mmio_wt __mmio_wv = (value); \
+        *(volatile __mmio_wt*)((uint8_t*)(base) + __mmio_rw.offset) = \
+            __mmio_rw.endian ? mmio_bswap(__mmio_wv) : __mmio_wv; \
+    })
+
+// Shifts and masks the bits of `value` to the position it needs to be stored in the register.
+#define mmio_field(field, value) ((MMIO_FIELD_TYPE(field))(((value) & mmio_width_mask((field).width)) << (field).shift))
+
+// Returns the contents of a `field` from a `value`.
+#define mmio_field_get(field, value) \
+    ((MMIO_FIELD_TYPE(field))(((value) >> (field).shift) & mmio_width_mask((field).width)))

include/zinnia/radix.h

@@ -0,0 +1,51 @@
+#pragma once
+
+#include <zinnia/errno.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#define RADIX_BITS  6
+#define RADIX_SLOTS (1 << RADIX_BITS)
+
+enum radix_tag : uint8_t {
+    RADIX_TAG_DIRTY,
+    RADIX_TAG_WRITEBACK,
+    RADIX_NUM_TAGS,
+};
+
+struct radix_node {
+    uint8_t shift;
+    uint8_t count;
+    uint8_t offset;
+    struct radix_node* parent;
+    uint64_t tags[RADIX_NUM_TAGS];
+    void* slots[RADIX_SLOTS];
+};
+
+struct radix_tree {
+    struct radix_node* root;
+};
+
+void radix_init(struct radix_tree* tree);
+void radix_destroy(struct radix_tree* tree);
+bool radix_empty(struct radix_tree* tree);
+
+void* radix_lookup(struct radix_tree* tree, uint64_t index);
+errno_t radix_insert(struct radix_tree* tree, uint64_t index, void* value);
+void* radix_remove(struct radix_tree* tree, uint64_t index);
+void** radix_slot(struct radix_tree* tree, uint64_t index);
+
+void radix_tag_set(struct radix_tree* tree, uint64_t index, enum radix_tag tag);
+void radix_tag_clear(struct radix_tree* tree, uint64_t index, enum radix_tag tag);
+bool radix_tag_get(struct radix_tree* tree, uint64_t index, enum radix_tag tag);
+bool radix_tagged(struct radix_tree* tree, enum radix_tag tag);
+
+size_t radix_gang_lookup(struct radix_tree* tree, uint64_t first, size_t max, void** out, uint64_t* out_index);
+size_t radix_gang_lookup_tag(
+    struct radix_tree* tree,
+    uint64_t first,
+    enum radix_tag tag,
+    size_t max,
+    void** out,
+    uint64_t* out_index
+);

include/zinnia/ringbuf.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <zinnia/errno.h>
+#include <zinnia/iovec.h>
+#include <stddef.h>
+#include <stdint.h>
+
+struct ringbuf {
+    uint8_t* data;
+    size_t capacity;
+    size_t head;
+    size_t len;
+};
+
+errno_t ringbuf_init(struct ringbuf* rb, size_t capacity);
+void ringbuf_fini(struct ringbuf* rb);
+
+static inline size_t ringbuf_len(const struct ringbuf* rb) {
+    return rb->len;
+}
+
+static inline size_t ringbuf_space(const struct ringbuf* rb) {
+    return rb->capacity - rb->len;
+}
+
+static inline void ringbuf_clear(struct ringbuf* rb) {
+    rb->head = 0;
+    rb->len = 0;
+}
+
+size_t ringbuf_write(struct ringbuf* rb, const void* src, size_t len);
+size_t ringbuf_read(struct ringbuf* rb, void* dst, size_t len);
+errno_t ringbuf_write_iter(struct ringbuf* rb, iovec_iter_t* iter, size_t len, size_t* out_written);
+errno_t ringbuf_read_iter(struct ringbuf* rb, iovec_iter_t* iter, size_t len, size_t* out_read);

include/zinnia/tailq.h

@@ -42,6 +42,14 @@
         (elm)->field.tql_prev = &(head)->tqh_first; \
     } while (0)
 
+#define tailq_insert_before(listelm, elm, field) \
+    do { \
+        (elm)->field.tql_prev = (listelm)->field.tql_prev; \
+        (elm)->field.tql_next = (listelm); \
+        *(listelm)->field.tql_prev = (elm); \
+        (listelm)->field.tql_prev = &(elm)->field.tql_next; \
+    } while (0)
+
 #define tailq_remove(head, elm, field) \
     do { \
         if (((elm)->field.tql_next) != nullptr) \

include/zinnia/vfs.h

@@ -179,7 +179,7 @@ struct vfs_node_ops {
         // VNODE_SYMLINK
         struct {
             // Reads the value of the symlink into `buf`.
-            errno_t (*read_link)(struct vfs_node* node, struct iovec_iter* iter, size_t* out_read);
+            errno_t (*read_link)(struct vfs_node* node, iovec_iter_t* iter, size_t* out_read);
         } symlink;
 
         // VNODE_DIR
@@ -264,8 +264,8 @@ struct vfs_node {
 };
 
 struct vfs_file_ops {
-    errno_t (*read)(struct vfs_file* file, struct iovec_iter* buffer, uint64_t offset, ssize_t* out_read);
-    errno_t (*write)(struct vfs_file* file, struct iovec_iter* buffer, uint64_t offset, ssize_t* out_written);
+    errno_t (*read)(struct vfs_file* file, iovec_iter_t* buffer, uint64_t offset, ssize_t* out_read);
+    errno_t (*write)(struct vfs_file* file, iovec_iter_t* buffer, uint64_t offset, ssize_t* out_written);
     errno_t (*ioctl)(struct vfs_file* file, uintptr_t request, uintptr_t arg, uintptr_t* out_result);
     errno_t (*sync)(struct vfs_file* file, bool data_only);
     errno_t (*mmap)(
@@ -411,17 +411,17 @@ errno_t vfs_file_open(
 
 // Reads from a `file` into a `buffer` from the current offset.
 // Returns the actual bytes read in `out_read`.
-errno_t vfs_file_read(struct vfs_file* file, struct iovec_iter* buffer, ssize_t* out_read);
+errno_t vfs_file_read(struct vfs_file* file, iovec_iter_t* buffer, ssize_t* out_read);
 
 // Same as `vfs_file_read`, but from a given offset.
-errno_t vfs_file_pread(struct vfs_file* file, struct iovec_iter* buffer, uint64_t offset, ssize_t* out_read);
+errno_t vfs_file_pread(struct vfs_file* file, iovec_iter_t* buffer, uint64_t offset, ssize_t* out_read);
 
 // Wites to a `file` from a `buffer` from the current offset.
 // Returns the actual bytes written in `out_written`.
-errno_t vfs_file_write(struct vfs_file* file, struct iovec_iter* buffer, ssize_t* out_written);
+errno_t vfs_file_write(struct vfs_file* file, iovec_iter_t* buffer, ssize_t* out_written);
 
 // Same as `vfs_file_write`, but from a given offset.
-errno_t vfs_file_pwrite(struct vfs_file* file, struct iovec_iter* buffer, uint64_t offset, ssize_t* out_written);
+errno_t vfs_file_pwrite(struct vfs_file* file, iovec_iter_t* buffer, uint64_t offset, ssize_t* out_written);
 
 // Performs a generic `request` on a `file`.
 // Returns the result in `out_result`.